How marble slabs and tiles are made
Marble is a recrystallised limestone or dolomite. It is far softer than granite, takes a high polish, and often carries veins and natural fissures that give each slab its look. India exported US$141.46 million of marble simply cut or sawn (HS 6802 21) in FY2025-26, and US$49.31 million of marble blocks (HS 2515) (Department of Commerce, TradeStat, provisional).
The best-known Indian marble is from Makrana in Nagaur district, Rajasthan. "Makrana Marble" is a registered Geographical Indication (application 405, certificate dated 30 March 2015), and Nagaur's One District One Product entry is "Granite/Marble - Makrana". Clear To Load is based in Jodhpur, in the same state.
Blocks are sawn into slabs on gang saws or wire saws. Because so many marbles have fissures, most slabs then go through a resin line: they are dried, resin is spread into the fissures and pores, and a fibreglass mesh is often glued to the back to hold the slab together. The face is then ground and polished, or honed for a matt finish. Tiles are cut from slabs, calibrated and chamfered. Feature walls and floors use slabs cut in sequence from one block, numbered so that neighbouring slabs can be laid as mirror images, a pattern called bookmatching.
What we check on marble
| Check | How it is checked | What fails |
|---|---|---|
| Fissures and cracks | Face wetted and viewed in raking light; fingernail across each line; the same line followed on the back | A line that opens, catches a nail or runs through the thickness |
| Resin fill | Filled areas compared with the sample for clarity and tint; checked level with the polish | Cloudy, yellowed, sunken or wrong-coloured fill; fill over a through crack |
| Back mesh | Mesh coverage and bond on the back; corner lifted gently | Mesh loose or missing where agreed; resin pools on the back that stop the slab bedding flat |
| Vein and bookmatch | Numbered slabs laid out in sequence and pairs flipped to check the mirror pattern | Slabs out of sequence, missing numbers, veins that do not meet |
| Polish and scratches | Gloss meter where specified; face viewed against a light at a low angle | Dull patches, swirl marks, scratches from handling |
| Thickness and size | Calliper at several points; tiles from several cartons; diagonals | Wedge-shaped slabs, tiles out of calibration |
| Stains | Faces and edges looked at for yellow, brown or rust marks | Stains from wet packing, iron spots, oil or resin marks |
| Edges | Every edge and corner; chamfer on tiles | Chips and spalls on visible edges |
Common marble slab and tile defects and how they are classed
| Defect | Typical cause | Class |
|---|---|---|
| Different marble supplied, or stone sold under an origin it does not have | Substitution | Critical (false description) |
| Crack through the slab hidden by resin | Weak block, handling, cosmetic fill | Major |
| Bookmatched set incomplete or out of sequence | Slabs sold or broken before packing | Major |
| Stain on a white marble face | Wet crate timber or cardboard, rusting strap | Major |
| Scratches across polished faces | Grit between slabs, no interleaving | Major or minor by extent |
| Cloudy or off-tint resin | Wrong resin or poor curing | Minor; major on a feature slab |
| Natural veining within the agreed range | The stone itself | Not a defect |
Cracked marble is a finding we have recorded. In Sample 04, a furniture inspection in Jodhpur, two black marble table tops had cracks and were to be replaced, and poor filling on cracks was found on another style. The same checks apply to slabs before they become tops.
Market rules for marble
- EU and GB. Marble slabs for cladding, tiles and floor and stair slabs come under EN 1469, EN 12057 and EN 12058. The manufacturer issues a declaration of performance and CE marking; the inspector checks that labels and documents match the stone shipped. See UKCA and CE marking.
- US. ASTM C503 is the material specification for marble dimension stone, classing marble as calcite or dolomite and setting minimum physical properties. Results come from a lab on your stone.
- Origin names. "Makrana Marble" is a registered GI in India. If you market stone under that name, ask for quarry and transport documents that tie the blocks to the registered area; the inspector checks them against the slabs.
- Crates. Wooden A-frames and crates must meet ISPM 15.
Packing, transit and your purchase order
Marble slabs travel on edge in wooden bundles, polished faces together with a plastic sheet between them. White marble needs dry packing: damp timber or cardboard against the stone can leave yellow or brown stains that set in the pores. Rusting steel straps leave orange marks. The inspector checks that crates are dry, interleaving is clean, straps do not touch the stone, and each bundle's slab numbers match the packing list. Load the bundles so they cannot lean or slide; see container loading supervision.
- Marble name, origin and finish; approved sample with limit pieces for colour and veining.
- What resin, mesh and fill colour is allowed, and that no fill may cover a through crack.
- Thickness and tolerance; tile calibration; minimum gloss.
- For feature work: slab numbering and bookmatch requirements.
- Packing: dry crates, plastic interleaving, ISPM 15, no direct strap contact.
For marble on tables, see marble and stone top furniture; for carved and inlaid pieces, marble and stone décor.
Sources
- IP India GI Registry: Makrana Marble, application 405
- Invest India: national ODOP product list (5 May 2023): Nagaur
- Department of Commerce, TradeStat: commodity-wise exports (HS 680221, 2515; FY2025-26 provisional)
- ASTM C503, Standard Specification for Marble Dimension Stone
- GOV.UK: Construction products regulation in Great Britain