Sixty-four stones, and not one of them is a number we made up. This page states the standard that governs each material, what the standard requires, and where the actual value for your slab has to come from — the test certificate that ships with the block.
A published property table is a catalogue average. A test certificate is your material.
Natural stone varies by block, by quarry bench, by season. Any supplier who publishes one absorption figure for a stone name is telling you about a sample they once tested, not about the slabs on your job. We publish the specification and the required minimum — then pull the certificate for the specific lot, before you write it into a schedule.
The technical tables below say what a stone is. These six pages say how to buy it: the match, the grade, what is on a shelf and what is not, how a code reads, and what happens between your elevation and the saw.
A block of marble is sawn into slabs the way a loaf is sliced. Each slab is a section through the same vein, a few millimetres further along. Slab 3 and slab 4 are nearly the same picture; slab 3 and slab 30 are two different stones. That sequence is the whole value of a matched wall — and it survives exactly one thing: being kept in order. So we number slabs at the saw, photograph them in order, and reserve them as a set.
Alternate slabs are flipped face-to-back, so every joint mirrors — a butterfly across the seam. Needs consecutive slabs, minimum two; the mirror only reads if the joint is tight. Standard for a feature wall, a fireplace, a vanity front.
Consecutive slabs laid in cut order without flipping. The vein travels one way across the whole run instead of mirroring; it reads as continuous stone rather than pattern. Use it where a book match would look staged, and on strongly directional material.
Slabs in cut order, joints falling where they fall. No balancing, no symmetry. The most economical option and the right one for large floors, where the eye reads material rather than composition.
Slabs cut to equal width so the run is symmetrical about its own centre, with a full slab at each end rather than a sliver. Costs yield. Worth it on anything with a visible start and finish.
An even number of equal slabs centred on a joint rather than on a slab. Used when a centreline in the room — a door, an axis, a mirror — has to land on the seam.
Four slabs mirrored about a centre point, horizontally and vertically. A radiating figure. Used for table tops, floor medallions and single large panels. Consumes four consecutive slabs to produce one panel.
ZS-014 · BLOCK 22 · SLABS 03–06 · BOOK MATCH · 4 SLABS · RUN 4.8 M
Every stone in the catalogue can be supplied at three levels of selection. The material is identical; what changes is how it is chosen, how much of the block is rejected to get it, and what we guarantee about consistency. Name the grade and everything below follows without restating it.
Normal variation for the species, including the range of colour and vein the quarry is producing that season. No lot reservation. Fastest and least expensive. Right for floors, back-of-house, large areas where variation reads as material.
A sample you approved, a photograph, or a named lot. Slabs outside that range are rejected before shipping. Some yield loss. Right for anything you have shown a client.
A specific numbered lot from one block, photographed and held for your project alone from the day you reserve it. Book, slip, quarter and centre-balance matching exist only at this grade. Highest yield loss, longest lead time, and the only grade that can promise a wall reads as one stone.
Almost nothing in this catalogue is on a shelf. That is deliberate, and it changes how you use it.
Current formats from the press line. Available in weeks, in quantity, to a published size.
The material exists; the specific slabs do not become yours until you reserve them. What you are buying is a selection out of what the quarry is producing now.
Cut-to-size, treads, inlay, basins, counters, cladding panels. There is no model number because there is no model. The dimension comes off your elevation.
ZS - 014 - P - 2 - BM
│ │ │ │ │
│ │ │ │ └─ MATCH BM book · SM slip · RM running
│ │ │ │ BAL balance · CB centre-balance
│ │ │ │ QM quarter · — none
│ │ │ └──────── THICKNESS cm. 1 tile · 2 slab · 3 counter
│ │ └────────────── FINISH P polished · H honed · B brushed
│ │ L leathered · F flamed · SB sandblasted
│ └───────────────────── MATERIAL the number printed under the swatch
└─────────────────────────── FAMILY ZS stone · DKZ decor tile · PC porcelain
CN hand-glazed çini · BN basinEverything ZARHA fabricates is made to your drawing. Nothing is picked from a size chart. That means one exchange of information before anything is cut, and it is the step that protects both sides.
Everything on this page falls on one side or the other. If it isn't here, we don't claim it.
Half the stones sold as “marble” are geologically something else, and the specification follows the geology, not the marketing. Here is how the four ZARHA families map to ASTM specification standards.
| Catalogue family | Usually classified as | Governing specification | Notes |
|---|---|---|---|
| Whites | Calcitic marble | ASTM C503, Class I | Carrara, Calacatta, Volakas, Thassos and the Turkish whites are calcite marbles. |
| Beige | Calcitic marble; one travertine | ASTM C503 / C1527 | Travertine is a separate specification with materially different limits — see below. |
| Black & brown | Calcitic marble; occasionally granite | ASTM C503 / C615 | Emperador, Marquina and Portoro are marbles. A stone sold as “black granite” is specified to C615. |
| Onyx & exotics | Onyx, quartzite, serpentine | C616 / C1526 / none | Quartzites go to C616 Class III. Green “marbles” are serpentines, C1526. Onyx has no ASTM specification. |
These are the published minimum values in the ASTM specifications themselves — the pass/fail line. They are not ZARHA figures and not typical values; a good slab usually clears them comfortably.
| Property | Marble · C503 | Granite · C615 | Quartzite · C616 Cl. III | Test method |
|---|---|---|---|---|
| Absorption by weight, max | 0.20 % | 0.40 % | 1.0 % | ASTM C97 |
| Density, min | 162 lb/ft³ · 2,595 kg/m³ 175 lb/ft³ dolomitic (Cl. II) | 160 lb/ft³ · 2,560 kg/m³ | 160 lb/ft³ · 2,560 kg/m³ | ASTM C97 |
| Compressive strength, min | 7,500 psi · 52 MPa | 19,000 psi · 131 MPa | 20,000 psi · 138 MPa | ASTM C170 |
| Modulus of rupture, min | 1,000 psi · 7 MPa | 1,500 psi · 10.3 MPa | 2,000 psi · 13.8 MPa | ASTM C99 |
| Flexural strength, min | 1,000 psi · 7 MPa | 1,200 psi · 8.3 MPa | — | ASTM C880 |
| Abrasion resistance, min Ha | 10 | 25 | 8 | ASTM C241 / C1353 |
The figures below are historical guideline data published by the Natural Stone Institute, not the requirement tables in ASTM C1527 and C1526. We separate them because a specifier is entitled to know which is which.
| Property | Travertine · guideline | Serpentine · guideline | Test method |
|---|---|---|---|
| Absorption by weight, max | 2.5 % | 0.20 % exterior 0.60 % interior | ASTM C97 |
| Density, min | 144 lb/ft³ | 168 lb/ft³ | ASTM C97 |
| Compressive strength, min | 5,000 psi interior 7,500 psi exterior | 10,000 psi | ASTM C170 |
| Modulus of rupture, min | 700 psi | 1,000 psi | ASTM C99 |
| Flexural strength, min | 500 psi | 1,000 psi | ASTM C880 |
| Abrasion resistance, min Ha | 10 | 10 | ASTM C241 / C1353 |
Judgement, not a test result. This is how we would advise on a first pass; the certificate, the finish, and the detail decide the final answer.
Polished marble in a commercial lobby will show traffic patterns within a year. Honed or leathered wears far more gracefully, and abrasion Ha 12 is the number to specify.
Calcite reacts with acid. Lemon, wine and descaler leave dull marks on polished marble — permanently, and no sealer prevents it. Honed hides it; clients who want zero patina should be steered to quartzite.
Green serpentines warp when set in wet cement mortar. They are installed with epoxy or a thin-set rated for moisture-sensitive stone, over a fully cured substrate. This is the single most common failure in green stone.
For any exterior application in a freeze-thaw climate we specify flexural strength (C880) measured after freeze-thaw cycling, not before. De-icing salts are a separate and harsher exposure again.
The same Carrara block yields four different DCOF values depending on how it leaves the polishing line. A DCOF figure quoted against a stone name, with no finish attached, is meaningless.
| ANSI A326.3 product use category | Requirement | Typical application |
|---|---|---|
| Interior, Dry (ID) | ≥ 0.42 dry DCOF | Areas expected to be dry in use — offices, retail sales floors away from entries. |
| Interior, Wet (IW) | ≥ 0.42 wet DCOF | Areas that are intermittently wet — residential baths, kitchens, entries. |
| Interior, Wet Plus (IW+) | Manufacturer-declared | Continuously or heavily wet interiors — pool surrounds, locker rooms, commercial kitchens. |
| Exterior, Wet (EW) | Manufacturer-declared | Exterior walking surfaces exposed to rain. |
| Oils / Greases (O/G) | Manufacturer-declared | Surfaces subject to oil or grease contamination. |
Every fabricated piece carries a permitted deviation. These are the industry tolerances published by the Natural Stone Institute — the values a fabricator is held to unless your specification tightens them.
| Condition | Tolerance | Applies to |
|---|---|---|
| Thickness — calibrated tile | ± 1/32″ · ± 0.8 mm | Nominal 1/4″ to 5/8″ |
| Thickness — slab, smooth finish | ± 1/8″ · ± 3 mm | Over 5/8″ to 2″ — covers 2 cm and 3 cm slabs |
| Thickness — heavy slab | ± 1/4″ · ± 6 mm | Over 2″ |
| Face dimension — calibrated tile | ± 1/32″ · ± 0.8 mm | Length and width |
| Face dimension — cut to size | ± 1/16″ · ± 1.5 mm | Pieces up to 6 ft |
| Face dimension — large pieces | ± 3/32″ to ± 1/8″ | Over 6 ft; over 50 ft² |
| Flatness — calibrated tile | ± 1/32″ in 2 ft · 0.8 mm in 600 mm | Smooth finishes |
| Flatness — cut to size, smooth | ± 1/16″ in 4 ft · ± 1.5 mm in 1.2 m | Smooth finishes |
| Flatness — textured or flamed | ± 3/16″ in 4 ft · ± 5 mm in 1.2 m | Textured finishes |
| Lippage — smooth calibrated tile | 1/32″ · 0.8 mm | Installed condition |
| Lippage — flamed or textured | not to exceed 3/16″ · 5 mm | Installed condition |
Natural stone has no shade-variation rating. The ceramic industry's V1–V4 scale is written for manufactured tile and does not apply here — so we handle range the way the stone industry actually does: with a physical control sample and a slab approval.
For any order above a nominal threshold we supply a range set — light, mid and dark of the block or lot — so the client approves the spread rather than a single flattering piece.
Full slabs are photographed square-on at known scale before cutting. For bookmatch and continuous-vein work, we lay out the sequence digitally and get it signed before a saw runs.
Where colour consistency is critical, the whole quantity is cut from one block and reserved. This constrains quantity and lead time — and it is the only real guarantee of match.
An approved control sample is retained by us and by you for the life of the job. It is the reference every delivery is judged against, and it is what settles a dispute.
Specify the cleaning regime with the same seriousness as the stone. It is the variable most likely to be wrong on site, and the only one that keeps costing money after handover.
| Family | Sealer | Initial | Reapplication guide |
|---|---|---|---|
| Marble — polished, interior | Impregnating, breathable | Before grouting; all six faces for wet areas | 2–5 years, by traffic and test |
| Marble — honed or leathered | Impregnating, breathable | Before grouting | 1–3 years — open surfaces absorb more |
| Travertine — filled | Impregnating; fill inspected first | All six faces before setting | 1–2 years |
| Travertine — unfilled | Impregnating; consider a grout-release coat | All six faces before setting | Annual |
| Serpentine | Impregnating, solvent-carried | Before setting; epoxy-set only | 2–4 years |
| Quartzite | Impregnating, optional on dense lots | Test absorption first — many need none | 3–5 years, or not at all |
| Onyx | Impregnating; resin backing checked | Before setting | 2–3 years |
On a facade or a rainscreen the stone is one component of an assembly. We are responsible for the material and its test data. The anchorage design belongs to your engineer of record, and we will not pretend otherwise.
California now regulates stone fabrication more strictly than any other state, and the regulation is aimed squarely at engineered stone. It matters to anyone specifying a surface in California — and it changes what a slab supplier is allowed to do.
| Material | Crystalline silica content, typical | Regulatory position |
|---|---|---|
| Marble | under 10 % | Lowest-silica surfacing material in common use. |
| Travertine, onyx, serpentine | low — calcite and silicate based | Comparable to marble; confirm per lot. |
| Granite | 30–45 % | Wet methods required for fabrication. |
| Quartzite | high — predominantly quartz | Treat as a high-silica natural stone; wet methods, full controls. |
| Engineered / artificial stone | over 90 % | The specific target of California's STOP Act. |
From 1 January 2026, wet suppression is mandatory for cutting, drilling, grinding, polishing, abrading and chiselling — and for cleaning up the dust afterwards.
Employees performing high-exposure tasks require training, with annual written attestation filed with state occupational safety officials.
The state's three-year shop certification application process must be in place.
Shop certification becomes mandatory — and slab suppliers are barred from selling to uncertified fabrication shops. That includes us.
Nothing here is a standard. It is our policy, stated plainly so it can be checked against your contract before anyone signs.
| Term | Position | Why |
|---|---|---|
| Attic stock | 5 % for standard floor and wall areas; 10 % for bookmatch, continuous vein and cut-to-size work — cut from the same block and crated separately. | A replacement piece from a different block will not match. Attic stock is the only real repair strategy for natural stone. |
| Reserve block | Where a project cannot tolerate variation, the block is purchased and held rather than the finished quantity. | Protects future phases and repairs against the block being sold on. |
| Transit damage | Inspect on arrival, note damage on the delivery receipt, and notify us within five business days with photographs of the crate and the piece. | Carrier claims have short windows. Photographs of an unopened damaged crate are what make a claim succeed. |
| Warranty | Twelve months from delivery against fabrication defects — dimension, finish, and cutting to approved drawings. Natural characteristics of the stone are not defects. | Veining, fissures, pitting, colour range and travertine voids are the material, not faults in it. The control sample is the reference. |
| Importer of record | On DDP terms ZARHA is the importer of record and duty is in the quoted number. On FOB or EXW the buyer imports and we supply the documentation. | Stated on the quote either way, so the landed cost is never a surprise at the port. |
| Documentation supplied | Test certificates, Safety Data Sheet, care and maintenance sheet, packing list, certificate of origin, and HTS classification on the commercial invoice. | Everything a submittal package and a customs broker need, in one set. |
A technical page is only worth reading if it says what it can't do. These are ours.
Name the materials and the application. Test certificates, DCOF for the finish you need, and physical samples — free, no commitment.