Every experienced stone importer has a story. A container arrives at the destination port, the doors are opened — and the stone inside does not match what was agreed. The color is darker than the sample. The blocks have hairline cracks that were not visible in the photos. The average block size is smaller than specified. The grade delivered is clearly lower than the grade invoiced.
These situations are not hypothetical. They occur regularly in the global stone trade, particularly in transactions between buyers and suppliers who have not yet established a deep working relationship. And they are almost entirely preventable — through rigorous quality inspection before the container is sealed and leaves the port of export.
This guide provides a complete, practical quality checklist for buyers of natural stone blocks from Iran — covering every inspection category from visual assessment to laboratory test verification, dimensional compliance to packaging standards. It also explains how to engage independent third-party inspection agencies (SGS, Bureau Veritas, Intertek) for buyers who cannot conduct inspections personally, with cost guidance and process information drawn from current market data.
Whether you are ordering Pietra Gray marble, Gohare beige limestone, Azna white crystal, or any of the other stones in the Iranmarbles range, this checklist applies directly.
Why Pre-Shipment Inspection Matters: The Economics
The case for pre-shipment inspection is straightforward when the economics are calculated honestly.
A 20ft container of Gohare beige limestone at $112/ton with 22 tons net weight has a stone value of $2,464 FOB. Add ocean freight to China ($600–900), port charges, and import duties, and the landed cost approaches $3,500–4,000 per container.
A pre-shipment inspection by SGS or Bureau Veritas costs approximately $300–$1,500 depending on scope — roughly 8–40% of the stone's FOB value. For a container worth $3,500–4,000 landed, this is a modest insurance cost against receiving off-grade or non-compliant material.
For higher-value shipments — a 40ft container of Pietra Gray marble at $220/ton carrying 25 tons net, worth $5,500 in stone value alone — the inspection cost represents an even smaller fraction of the total shipment value.
An inspection check costs an average of $800–3,000 depending on scope and the parameters tested. But the cost of receiving non-compliant stone — reprocessing loss, production downtime, client complaints, replacement sourcing — almost always exceeds this by a significant multiple.
The rule of thumb used by experienced stone importers: Pre-shipment inspection is economically justified on any order above $3,000 FOB value. Below that threshold (very small trial samples), the inspection cost may be disproportionate — but the sample itself serves as the quality reference for future orders.
The Two Inspection Approaches: Personal Visit vs Third-Party Agency
Before walking through the checklist, understand your two options for conducting inspection:
Option A — Personal visit or appointed agent
- You or your representative inspects blocks at the supplier's storage yard before loading — maximum control over acceptance and rejection
- Practical for buyers in neighboring countries (Turkey, UAE, India), large recurring orders, or first relationships with a new supplier
- Iranmarbles accommodates personal visits to the Khorramabad facility — coordinate timing with your sales contact
Option B — Third-party inspection agency
- Appoint SGS, Bureau Veritas, or Intertek to inspect on your behalf and issue a formal report before the container is sealed
- Practical for international buyers, L/C payment requiring inspection certificates, or any buyer wanting independent grade verification
- Cost guidance: approximately $300–$1,500 depending on scope — basic visual check at the lower end, laboratory sampling at the higher end
Bureau Veritas carries out physical inspection of goods in the country of export pre-shipping, establishing the exact nature of the goods. Bureau Veritas can make a quotation in under 24 hours and inspectors communicate results in real time in case of detected divergence.
The Complete Pre-Shipment Inspection Checklist
Category 1: Documentation Verification
Before any physical inspection begins, verify that the documentation matches your contract.
Proforma Invoice match: Confirm the stone type, grade, quantity (tons), block count, and unit price on the supplier's invoice match the signed Proforma Invoice exactly. Any discrepancy — even in the stone's description or grade designation — should be resolved before inspection proceeds.
Laboratory test report: Request the current laboratory test report for the specific stone type being shipped. For Iranmarbles products, these reports should confirm the published technical specifications:
| Stone | Key specification to verify |
|---|---|
| Pietra Gray Marble | Water absorption ≤0.42%, compressive strength ≥1,350 kg/cm² |
| Harsin Beige Marble | Water absorption ≤0.96%, compressive strength ≥1,180 kg/cm² |
| Gohare Beige Limestone | Water absorption ≤1.27%, compressive strength ≥1,180 kg/cm², abrasion ≤2.9 mm |
| Patris Gray Limestone | Water absorption ≤1.82%, abrasion ≤2.8 mm |
| Azna White Crystal | Water absorption ≤0.22%, compressive strength ≥1,000 kg/cm² |
| Aligudarz White Crystal | Water absorption ≤0.10%, compressive strength ≥910 kg/cm² |
The laboratory test report should be from an accredited testing facility and should reference the applicable standard — ASTM C503 (marble), ASTM C568 (limestone), EN 1341/1342/1343 (European equivalents), or the equivalent Iranian national standard (ISIRI).
Certificate of Origin: Confirm a Certificate of Origin (CO) is available, issued by the Iran Chamber of Commerce, Industries, Mines and Agriculture (ICCIMA). The CO is required for customs clearance in most destination countries and is essential for preferential duty rate claims where applicable.
Phytosanitary Certificate: All Iranian stone exports use wooden packaging (timber cradles and strapping). The wood must comply with ISPM 15 (International Standards for Phytosanitary Measures No. 15) — heat-treated and stamped with the official IPPC mark. The Phytosanitary Certificate, issued by Iran's Plant Protection Organization, confirms compliance. Without this document, your shipment may be held at the destination port for fumigation or rejected outright in countries with strict biosecurity rules.
Category 2: Quantity Verification
Block count: Count the total number of blocks in the storage yard allocated to your order. Confirm it matches the block count on the Proforma Invoice and the packing list.
Net weight estimation: Weigh a representative sample of blocks (or use the supplier's weight records if calibrated scale documentation is available) to estimate total net stone weight. Compare against the contracted quantity in tons.
Gross weight and container capacity check: Confirm that the total gross weight (stone + packaging) is within the maximum payload of the nominated container type — typically 28 tons for a 20ft container. Overloaded containers create serious safety and logistics problems at destination ports.
Category 3: Visual Quality Assessment
This is the core of any stone block inspection — and the area where professional judgment matters most. Once raw blocks are quarried, they are inspected for uniformity, density, and absence of micro-cracks. Each block is graded based on its intended use — architectural cladding, paving, landscaping, interior surfaces, etc. This selection process is done manually and visually by highly trained professionals who understand the nuances of each type of stone.
Background color consistency: Assess every block individually against the contracted grade description and the approved reference sample. For each stone type, know what the grade requires:
- Exportable Quality Gohare: Solid light beige, no streaks, no rust halos, no dark patches
- Exportable Quality Pietra Gray: Consistent charcoal-gray background, controlled white veining
- Exportable Quality Azna Crystal: Bright white, diagonal gray/black streaks, no yellow halos
- Super Quality (any stone): Close to exportable but minor allowable color variation within defined tolerance
Photograph each block face individually during inspection. These photos become your documentary record if a dispute arises after delivery.
Crack and fracture assessment: Examine all six faces of each block systematically for:
- Through cracks — fractures that penetrate the full depth of the block. Any through crack is grounds for rejection regardless of grade
- Hairline surface cracks — fine surface fractures that may or may not penetrate deeply. Acceptable tolerance varies by grade (exportable quality: none; lower grades: defined maximum)
- Natural fissures — geological planes of weakness within the stone. Must be assessed for their depth and whether they will cause block breakage during gang saw cutting
Run your hand across each block face — fingertips detect surface irregularities, hairline cracks, and rough zones that can be difficult to see visually under certain lighting conditions. Wet the block face with water — cracks and fissures become dramatically more visible on a wet stone surface than a dry one.
Vein character assessment: For veined stones (Pietra Gray marble, Harsin marble, Azna crystal, Aligudarz crystal): assess whether the vein density, character, and distribution match the contracted grade.
Excessive veining that fragments the background color, iron staining along vein lines (rust halos), or vein patterns significantly different from the reference sample are grounds for grade downgrade or rejection.
Surface contamination and staining: Examine all block faces for iron rust staining, oil or chemical staining from machinery contact, cement or mortar contamination from storage yard surfaces, and biological staining (moss, algae, root marks) from prolonged outdoor storage.
Minor surface contamination that does not penetrate the stone is acceptable for lower grades — the stone's cut interior will be clean. But heavy contamination that might indicate deeper staining within the block warrants rejection.
Edge and corner integrity: Assess the condition of block edges and corners. Some chipping of edges and corners is normal and acceptable — it occurs during extraction and transport. Excessive edge damage that would reduce usable block dimensions below contracted minimums, or corner chips that indicate brittleness in the stone's edge zone, should be noted and discussed with the supplier.
Category 4: Dimensional Compliance
Minimum block dimensions: Measure the length, width, and height of every block with a measuring tape or laser distance meter. Compare against the contracted minimum dimensions — typically specified in the Proforma Invoice as something like "minimum 150×100×80 cm six-sided clean cut."
Any block that falls significantly below contracted minimum dimensions should be flagged. Small dimensional shortfalls (2–5 cm under minimum) may be acceptable depending on your production equipment tolerances; larger shortfalls are grounds for rejection.
Six-sided cut quality: Confirm that all six faces of each block are cleanly cut — no rough quarry faces left on any side. A six-sided clean-cut block is the standard export specification for a reason: it is the only format that can be efficiently loaded onto a gang saw without additional trimming. Blocks with uncut quarry faces on any side may not be loadable on your equipment, or may yield significantly less usable stone.
Block shape regularity: Check that block faces are reasonably flat and parallel — not bowed, twisted, or irregular. Minor surface undulation from wire saw cutting is normal and acceptable. Significant bowing or wedge-shaped blocks (significantly wider at one end than the other) can cause problems in gang saw loading and should be flagged.
Dimensional tolerance: Professional stone inspection uses dimensional tolerance standards — typically ±2–3 cm on each dimension for export blocks. Blocks within tolerance are accepted; blocks outside tolerance are flagged for review. Your inspection agency will apply an AQL (Acceptable Quality Level) sampling plan to the total block count and assess dimensional compliance statistically.
Category 5: Grade Compliance Assessment
Comparison against reference sample: Your approved reference sample — the physical 30×30 cm cut section provided by the supplier during the sales process — is your contractual benchmark for color and vein character. Every block in the shipment should be assessed against this reference. If a significant proportion of blocks clearly fall below the reference quality level, the shipment does not meet the contracted grade specification.
Grade consistency within the lot: Within a single container load, assess how consistent the blocks are with each other. For Exportable Quality orders, all blocks should be visually similar — the same color tone, similar vein character, consistent background uniformity. Significant visible variation between blocks suggests the lot includes material from multiple grade levels — a common issue when suppliers mix grades to fulfill orders.
Grade-specific acceptance criteria: Apply the specific criteria for each grade as described in the natural stone block grades guide. The key distinction between adjacent grades is usually the background color brightness and the degree of vein variation — criteria that are visible to an experienced eye once you understand the grading system.
Category 6: Packaging and Loading Compliance
Wooden cradle construction: Each block should be secured on a wooden timber cradle — a frame of heat-treated timber that supports the block's weight during loading, shipping, and unloading. Assess that timber is adequate gauge for the block weight, ISPM 15 heat treatment stamp (HT mark) is visible on the timber, and the cradle is structurally sound.
Steel strapping: Blocks should be secured to their cradles with steel strapping bands, tensioned and sealed with crimped clips. Count the number of strapping bands per block — typically 2–4 depending on block size. Confirm strapping is tight and properly secured. Loose strapping is a container loading safety concern.
Container loading plan: For large block shipments, request the supplier's container loading plan — a diagram showing how blocks are positioned within the container. Blocks should be loaded with their longest dimension running parallel to the container length, heaviest blocks on the bottom. Confirm the plan is logical and that the total gross weight is within container payload limits.
Container condition: Before loading begins, inspect the interior of the nominated container for water ingress evidence, sharp protrusions, clean floor, and proper door sealing. Request the Container Inspection Report (EIR) from the shipping line — this documents the container's condition at the time of release.
Category 7: Post-Inspection Documentation
After inspection is complete, the following documents should be issued and transmitted to the buyer:
Inspection Report: A formal written report documenting all findings: quantity verified, visual quality assessment results, dimensional compliance, grade compliance determination, packaging condition, and any non-conformances noted with recommendations (accept/reject/conditional acceptance).
Inspection Certificate: For third-party inspections, a formal certificate from SGS, Bureau Veritas, or Intertek confirming the inspection was conducted and the goods met (or did not meet) the contracted specifications. This certificate may be required by your bank if payment is via Letter of Credit.
Container seal number: After loading is complete and the inspection is satisfactory, record the container seal number — the numbered security seal applied to the container doors. This number appears on the Bill of Lading and confirms the container has not been opened since inspection.
Photographic documentation: Ensure the inspection includes systematic photography of every block face, the loaded container interior, the packaging condition, and any non-conformances. These photos are your documentary evidence for any subsequent insurance claim or supplier dispute.
Engaging SGS, Bureau Veritas, or Intertek for Iran Inspections
All three major international inspection agencies operate in Iran and can conduct pre-shipment inspections at stone supplier facilities.
How to engage an inspection agency
Step 1: Contact the agency's Iran office or your country's local office at least 5–7 business days before your intended inspection date. 5 days before shipment is enough for products for which acceptable proof of compliance is provided.
Step 2: Provide a clear inspection brief including:
- Supplier name and facility address (Iranmarbles: Industrial Park, Khorramabad, Lorestan, Iran)
- Stone type, grade, and quantity to be inspected
- Contract specifications (minimum block dimensions, grade description, weight)
- Reference sample description or photos
- List of specific parameters to be checked (from this checklist)
- Any laboratory testing requirements (water absorption verification, compressive strength)
Step 3: Agree on cost and payment. First tier quality control companies like SGS offer product inspection services in the price range of $300–$1,500. A basic visual and quantity inspection for a single container is typically at the lower end; full inspection including laboratory sample collection and testing adds cost and time.
Step 4: The agency schedules the inspection with the supplier. Bureau Veritas's PSI focuses on quality, quantity, value, and compliance, carried out when goods are 100% finished and 80% packed.
Step 5: Receive the inspection report — typically within 24–48 hours of the physical inspection. Review findings and decide whether to authorize container loading and sealing.
What to specify in your inspection brief for stone blocks
A generic inspection request will get a generic inspection. To get maximum value from your inspection investment, be specific:
- Visual color assessment: Compare every block against the reference sample photo I will provide. Note any blocks that are darker/lighter/more veined than the reference.
- Crack assessment: Check all six faces of every block for cracks. Reject any block with a visible through crack.
- Dimensional check: Measure length, width, and height of every block. Flag any block below specified minimum dimensions.
- Six-sided cut verification: Confirm all faces are machine-cut, no quarry faces present.
- Packaging check: Verify ISPM 15 stamp on all timber, steel strapping tension and quantity per block.
- Quantity verification: Count blocks and estimate total net weight.
- Photographic documentation: Photograph every block face, all four corners of container loading, and any non-conformances.
The Complete Inspection Checklist: Quick Reference
Use this summary checklist for every stone block order:
| Category | Checkpoint | Pass criteria |
|---|---|---|
| Documentation | PI match | Stone type, grade, quantity match contract |
| Documentation | Lab test report | Published specs confirmed |
| Documentation | Certificate of Origin | Issued by ICCIMA |
| Documentation | Phytosanitary Certificate | ISPM 15 compliant timber confirmed |
| Quantity | Block count | Matches PI and packing list |
| Quantity | Net weight | Within ±5% of contracted quantity |
| Visual | Background color | Matches reference sample and grade spec |
| Visual | Crack assessment | No through cracks; hairlines within grade tolerance |
| Visual | Vein character | Within grade tolerance |
| Visual | Surface contamination | No deep staining; minor surface marks acceptable |
| Dimensional | Minimum dimensions | All blocks ≥ contracted minimum (L×W×H) |
| Dimensional | Six-sided cut | All faces machine-cut; no quarry faces |
| Dimensional | Shape regularity | No significant bowing or wedge shape |
| Grade | Reference comparison | Majority of blocks match reference quality |
| Grade | Lot consistency | Blocks visually consistent with each other |
| Packaging | Wooden cradle | Adequate gauge; ISPM 15 HT stamp visible |
| Packaging | Steel strapping | Tight, properly sealed, minimum 2 bands per block |
| Container | Interior condition | No water ingress, clean, no protrusions |
| Post-inspection | Inspection report | Issued and transmitted before loading |
| Post-inspection | Container seal | Number recorded and matches B/L |
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Frequently Asked Questions
Is pre-shipment inspection mandatory for Iranian stone exports?
No — pre-shipment inspection is voluntary for the buyer in most cases. However, it is strongly recommended for first orders from a new supplier and for any order above $3,000 FOB value. Some payment methods — particularly documentary Letters of Credit — may require an inspection certificate as a condition of document presentation; check with your bank.
How much does a pre-shipment inspection cost for Iranian stone blocks?
First tier quality control companies like SGS offer product inspection services in the price range of $300–$1,500. For a basic visual, quantity, and dimensional check on a single container load of stone blocks, expect to pay approximately $400–$800. If laboratory sampling and testing (water absorption, compressive strength verification) is included, costs rise to $1,000–$2,000 depending on scope and the number of samples tested.
Which inspection agency should I use for Iran?
SGS, Bureau Veritas, and Intertek all operate in Iran and are internationally recognized. All three produce inspection reports that are accepted by banks (for L/C purposes), customs authorities, and insurance companies. Bureau Veritas has particular experience in Middle East operations. For most stone buyers, the choice between the three is based on the agency's local responsiveness and your existing relationship.
Can I inspect the blocks myself at Iranmarbles' facility?
Yes. Iranmarbles welcomes buyer visits to its Khorramabad storage facility for pre-shipment inspection. Coordinate the timing of your visit with your sales contact — typically 3–5 days advance notice is sufficient to ensure your reserved blocks are accessible and the team is available. Contact us to arrange a visit.
What happens if the inspection reveals non-compliant blocks?
A finding of non-compliance triggers a discussion between you and the supplier. Options typically include: replacement of non-compliant blocks with acceptable material, price adjustment to reflect the actual grade delivered, or partial rejection and partial acceptance. A professional supplier like Iranmarbles will work with you to resolve non-conformances before the container is sealed rather than after it arrives at your port.
Does Iranmarbles provide laboratory test reports for its products?
Yes. Current laboratory test reports are available on request for all products — Pietra Gray marble, Harsin marble, Gohare limestone, Patris limestone, Azna crystal, and Aligudarz crystal. Reports confirm water absorption, compressive strength, abrasion resistance, porosity, and specific weight. Contact our team to request documentation.
Inspection Support from Iranmarbles
Iranmarbles (Kaniyar Sang Zagros) actively supports buyer quality assurance at every stage. We provide current high-resolution photos of available block stock before order confirmation, apply transparent grading at the quarry face and storage yard, and accommodate pre-shipment inspections by SGS, Bureau Veritas, Intertek, and buyer-appointed agents at our Khorramabad facility.
Laboratory test reports for all products are available on request. We prepare all required export documents — Commercial Invoice, Packing List, Certificate of Origin, Phytosanitary Certificate — to the standard required for smooth customs clearance. Read more in our stone import guide.
To request samples, discuss inspection arrangements for your order, or request a Proforma Invoice, contact our sales team at info@iranmarbles.org or WhatsApp +98 935 700 0285. We respond to all inquiries within 24 hours.