How to Order a Calibrated Layout

By the Byrex Gems team, Toronto · Published 6 October 2026

How to brief a supplier for a calibrated or graduated gemstone layout: colour range, millimetre tolerances, carat weight, treatment, lab reports, colour matching, lead times and memo.

A line bracelet, a rivière or an eternity band is only as good as its weakest stone. One sapphire that reads a shade lighter, one ruby with a brownish cast, or one stone that sits a fraction higher than its neighbours, and the piece looks assembled rather than designed. That is why designers and manufacturers buy matched stones as a layout, not one by one. This guide explains what a layout is, how to brief a supplier so that the stones arrive as you imagined them, how colour matching is judged, and the mistakes that most often cost time and money.

What a layout is

A layout is a set of loose stones selected to be set together in one piece of jewellery. The stones are matched for colour, shape, cut and size, and the set is priced and sold as a unit. Layouts fall into two broad types:

Calibrated layouts: every stone is cut to the same millimetre size, for example 4.0 × 3.0 mm ovals or 3.0 mm rounds. These suit line bracelets, eternity bands, channel-set rows and halo or cluster pieces, where the mounting is built around a fixed seat size.
Graduated layouts: the stones step up in size towards the centre, as in a classic rivière necklace or a graduated bracelet. The key figures are the piece count, the size of the largest and smallest stones, and the steps in between.

Matched pairs for earrings and three-stone sets for rings are the smallest form of the same idea. The more stones a layout holds, the harder it is to match, and the effort rises sharply in fine colours such as vivid blue sapphire or saturated red ruby, where very few stones of the right size and colour exist at any one time.

What "calibrated" really means

Calibration is a cutting discipline. To finish a stone at a set size, the cutter must start with a preform slightly larger than the target. In a review of the Jaipur cutting industry, Gems & Gemology gave the example of a 6 × 4 mm oval, which needs a preform of at least 6.2 × 4.2 mm. The same study described one firm cutting to a 0.2 mm tolerance for television jewellery and to 0.1 mm for its designer work, and noted that cutters also control crown height and pavilion depth so that the weight of each stone stays within what customers will accept (GIA, Gems & Gemology).

For a jeweller, depth matters as much as length and width. Two 4 × 3 mm ovals of different depths will not sit at the same height in a channel or under shared prongs, and a stone that is too deep for the seat may need the mounting altered. When you brief a supplier, give the depth range your mounting can take, not only the outline size.

How to brief a supplier

A clear brief is the single best way to shorten the search. Set out each of the following, in writing:

Stone and variety. Blue sapphire, pink sapphire, ruby, emerald, spinel, tsavorite and so on. If origin matters to you or your client, say so, and say whether it must be supported by a laboratory report.
Colour and colour range. Describe the target colour as precisely as you can, ideally with a reference stone or a photograph taken in daylight. State how much variation you will accept. A tight range costs more and takes longer to fill than a broad one.
Shape and exact calibration. Give the shape and the size in millimetres, with your tolerance for each dimension, for example 4.0 × 3.0 mm ±0.1 mm, and the acceptable depth range.
Piece count and graduation. State the number of stones. For a graduated layout, give the size of each step or a drawing of the piece, including which stones are paired either side of the centre.
Total carat weight. Give a target total weight with an acceptable range. Weight follows from size and depth, so a tight weight range in a calibrated layout is in effect a tight depth range.
Treatment. State whether the stones may be heated, must be unheated, or may carry any other treatment. Do not leave this open. A layout should not mix heated and unheated stones, and it should never include stones with different treatments unless you have agreed to it.
Laboratory reports. Decide whether you need a report for each stone or a single report covering the layout (see below).
Clarity and cutting standard. Say whether you need eye-clean stones, whether minor inclusions are acceptable in small sizes, and how much variation in brightness you will accept from stone to stone.
Timing and use. Say when you need the stones and what they are for. A supplier who knows the stones are going into a channel-set band will check different things from one who knows they are for a cluster.

Individual reports or one report for the layout

Laboratories issue different documents for single stones and for groups. SSEF, for example, issues its Gemstone Report for a single loose natural stone, while its Test Report is the document used for mounted stones, jewellery and lots of gemstones (SSEF). Other laboratories have their own arrangements, so confirm with the laboratory before you rely on any particular format.

Individual reports give the most information, because each stone is identified and its treatment stated on its own document. They also add cost, which is usually justified for larger or unheated stones and rarely for small calibrated goods. A single report for the layout confirms what the stones are and how they have been treated as a group, which is often all that a bracelet of small sapphires needs. Whichever you choose, check that the report describes the same number of stones, the same total weight and the same treatment as the layout you are buying.

How colour matching is judged

Colour is the hardest part of any layout and the part most open to dispute. For sapphire, GIA notes that colour has the greatest influence on value and that colour zoning, areas of different colour within one stone, is a common characteristic that cutters manage by orienting the stone (GIA). In a layout, zoning or an uneven cut can make one stone read differently from its neighbours even when the rough was similar.

Experienced matchers look at three things: hue (the basic colour and any secondary colour, such as violet in blue sapphire or orange in pink sapphire), tone (how light or dark the stone is) and saturation (how strong the colour is, as against greyish or brownish). A stone can match in hue and still stand out because it is darker or greyer. Brightness also matters: a stone cut too shallow can show a washed-out centre, and one cut too deep can look dark, so a well-matched layout is matched in cutting as well as in colour.

Lighting changes everything. Writing for JCK, Richard Drucker of Gemworld International advises viewing coloured stones in north daylight or the best daylight-equivalent lighting available, and warns that artificial light can alter appearance; incandescent light, for example, makes a ruby look redder and hides a secondary purple (JCK). A practical routine for a layout:

Lay the stones out in the order they will be set, on a neutral white or grey surface.
Look at them in daylight-equivalent light first, then under the warmer light of a showroom, and note any stone that changes more than the rest.
Look from normal viewing distance as well as under the loupe. A layout is judged by how it reads as a whole.
Photograph the layout in one frame, under one light, so that you and your supplier are discussing the same image.

Lead times

How long a layout takes depends almost entirely on where the stones come from. A layout already assembled from stones in stock can be ready to view in days. One that has to be built by pulling stones from several parcels takes longer, and one that needs stones cut to order, or sourced from cutters and dealers in other countries, can take weeks or months, particularly for fine colours, unheated material, larger calibrated sizes or very tight tolerances. Laboratory reports add further time, since stones must be sent to the laboratory and returned.

The way to shorten a lead time is to widen something: the colour range, the size tolerance, the treatment, or the piece count. A good supplier will tell you which of these would make the most difference.

Memo and approval

In the trade, stones are often sent on memo: a consignment arrangement under which the stones remain the supplier's property until paid for, and are either paid for or returned within an agreed period. Memo lets a designer see the stones in person, or show them to a client, before committing. It also carries risk for both sides. Jewelers Mutual lists loss, damage or theft, unclear payment terms, goods being mixed up with another supplier's, and the merchant's insolvency among the main risks (Jewelers Mutual). A Rapaport article on the risks of memo recommends a signed memo, full insurance, and photographs and documentation of the goods before they leave (Rapaport).

For a layout, the memo should list the piece count, the total weight, the size range, the treatment and any report numbers, so that what comes back can be checked against what went out. Keep the stones in the parcel paper they arrived in until the layout is approved, and do not set, re-cut or separate any stones while they are on memo.

Mistakes to avoid

Briefing by outline only. Giving the length and width without a depth range is the most common cause of stones that do not sit properly in the mounting.
Judging colour under one light. A layout matched under shop lighting can separate in daylight. Check both.
Leaving treatment open. A layout that mixes heated and unheated stones, or includes a stone with a different treatment, cannot be described or priced as one.
Too tight a tolerance for the stone. A 0.05 mm tolerance in a fine colour may simply not exist in the market. Ask what is realistic before you design around it.
No spare stone. If a stone is damaged in setting, a replacement that matches the rest can be hard to find. Consider asking for a spare, or keep the supplier's details for that layout.
Not checking the paperwork. Make sure the piece count, total weight and treatment on the invoice, memo and any report all agree with the layout in front of you.

Layouts from Byrex Gems

Byrex Gems has supplied fine coloured gemstones and natural fancy colour diamonds to the jewellery trade since 1988, and we are members of AGTA and CJA. Layouts are filmed in-house, unedited and unfiltered, and further images or video of any layout are available on request. You can see current layouts on our Gemstone Layouts page, or use the Layouts, Pairs and 3-pc sets filters in Stone Search, combined with Unheated if you need it. Many layouts are not shown online, and what we do not hold ourselves we can source for you, so send us your brief. Approved trade buyers see prices online; to apply, open a trade account.

To discuss a layout, email info@byrex.com or send a WhatsApp message to +1 (437) 450-3786.