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Calibrated Gemstones

Calibrated gemstones are stones cut to standard millimetre sizes and shapes so that they fit ready-made mountings and repeat across a production run without individual fitting. For a manufacturer, consistency of size, depth and colour across a parcel matters more than any single stone, and a reliable supplier is judged on how little sorting the bench has to do. Byrex Gems supplies calibrated sapphire, ruby, emerald, spinel, tsavorite, tourmaline and other stones to the trade from Toronto, filmed unedited, with prices for approved buyers and viewings by appointment.

Where to buy calibrated gemstones in Toronto

Byrex Gems lists 135 calibrated gemstones online today. 48 of them come with a report from laboratories including GRS, GIA, CDC and Argyle. Origins include Sri Lanka (Ceylon), Burma (Myanmar), Zambia and Mozambique. Viewings are at our Toronto office, 27 Queen Street East, Suite 407, steps from Queen subway station, by appointment. We have supplied coloured gemstones and natural fancy colour diamonds to jewellers and designers since 1988, and welcome private clients by appointment. Prices are shown to approved trade accounts; private clients can ask us on WhatsApp, where we reply within 12 hours, or by email within 24 hours. Every stone ships insured, worldwide.

Among the calibrated gemstones listed today: 3.38 ct Emerald Cut Emerald Pair (1.87 + 1.51 ct), Zambia, 2.40 ct Square Emerald Cut Emerald Pair (1.29 + 1.11 ct), GIA, Brazil, 128.52 ct Square Princess Cut Sapphire Layout (302 pcs), Madagascar Heated, 79.19 ct Oval & Marquise Sapphire Layout (70 pcs), Unheated, 40.06 ct Round Blue Sapphire Layout (27 pcs), Ceylon Heated, 39.67 ct Round Blue Sapphire Layout (29 pcs), Ceylon Heated, 39.08 ct Round Blue Sapphire Layout (29 pcs), Ceylon Heated, 36.71 ct Round Blue Sapphire Layout (24 pcs), Ceylon Heated, 11.89 ct Square Emerald Cut Emerald Pair (5.77 + 6.12 ct), GRS, Zambia No Oil, 11.37 ct Pear Emerald Pair (5.85 + 5.52 ct), Zambia, 11.05 ct Round Ruby Layout (36 pcs), Burma Heated, 10.56 ct Oval Ruby Pair (5.55 + 5.01 ct), GIA, Mozambique Heated and 123 more.

What calibrated means and the standard sizes

A calibrated stone is cut to a stated outside dimension in millimetres, within a small tolerance, rather than to whatever the rough allows. The purpose is interchangeability: a setter can drop a 3 mm round into a 3 mm seat, a 6 by 4 mm oval into a 6 by 4 mm head, and repeat the operation across a hundred pieces without adjusting each one.

The standard sizes follow the mountings and setting tools of the jewellery industry. Rounds run from 1 mm upward in steps of a tenth or a quarter of a millimetre at the small end and in half-millimetre steps above about 3 mm. Ovals, cushions, pears and emerald cuts are quoted length by width: 5 by 3, 6 by 4, 7 by 5, 8 by 6, 9 by 7 and 10 by 8 mm are the common oval and cushion sizes; 5 by 3, 6 by 4 and 7 by 5 mm are the usual pears; princess and square cuts are quoted by side.

Most calibrated goods are cut in the centres that specialise in volume, in Thailand, Sri Lanka, India and China, from rough that is sorted and often heated to bring the colour of a parcel together.

Tolerances, depth and how a parcel is matched

The tolerance on a calibrated stone is the amount by which its measured dimension may differ from the nominal size. The trade accepts around a tenth of a millimetre on small rounds and a little more on larger fancy shapes, but the figure should be agreed with the supplier. Depth is the dimension most often overlooked. Two 6 by 4 mm ovals of the same outline can differ by a third in depth, which changes how they sit in a head and how high the finished piece stands, so a good parcel is sorted for depth as well as outline.

Colour matching is the other half of calibration. A parcel is sorted under one light source, usually daylight-equivalent, for hue, tone and saturation, so that the stones read as the same colour when set side by side. The buyer specifies how tight the match should be; a tennis bracelet or an eternity band needs a closer match than scattered accent stones. Clarity is sorted to a stated standard, commonly eye-clean viewed from the top, and cut is checked for consistent crown height, table size and girdle thickness.

Treatment runs across the parcel. Calibrated sapphire and ruby are generally heated, emerald is clarity-enhanced, and the disclosure applies to the lot.

How manufacturers order calibrated stones

An order for calibrated goods states the species and colour, the shape and nominal size, the quantity in pieces or in carats, the quality standard for colour and clarity, the treatment requirement and the tolerance. Lead time depends on whether the parcel exists in stock or must be cut or assembled, and on the size of the run.

Manufacturers usually order with a particular setting style in mind, and it pays to say so. Prong and bezel settings forgive a small variation in outline; channel, bead and cast-in-place settings do not, and the parcel should be sorted more tightly for them. For pavé and micro-pavé work, the depth and the girdle thickness matter as much as the outline, because the stones sit shoulder to shoulder in a drilled seat.

Byrex supplies calibrated stones from its own stock and sources parcels to a brief through its offices and partners, and lists two stones as a pair only when the parcel paper or report describes them as one, otherwise as a close match.

What drives the value of calibrated goods

In calibrated goods the value of the parcel lies as much in the sorting as in the stones. A parcel that is tightly matched for colour, depth and outline saves the manufacturer the cost of sorting and rejects, and that saving is priced in; a loosely matched parcel of the same species and size is worth less even when the individual stones are fine. The tighter the specification, the more rough is rejected to meet it, and the price per carat rises accordingly.

Colour sets the base. Within sapphire, a parcel of saturated blue is worth many times a parcel of pale or greyish blue in the same size, and the same holds for ruby, emerald, tsavorite and spinel. Treatment affects the price in the same way as for single stones: unheated sapphire and ruby parcels and lightly enhanced emerald parcels carry premiums.

Size has a particular effect in calibrated goods. Because large rough is cut into single stones of the best possible weight, calibrated stones become scarce and expensive quickly above about 7 by 5 mm in fine colour, and a parcel of matched 10 by 8 mm sapphires in good blue is a serious purchase.

Calibrated stones, pairs, suites and what Byrex supplies

Calibration is the foundation of three related products. A matched pair is two stones of the same shape and nominal size, sorted for colour, depth and cut to be set together in earrings or as side stones; a pair is a calibrated parcel of two with a tighter match than a production lot. A suite is a group of stones, often of several shapes and sizes, matched to be worn together across a necklace, earrings, bracelet and ring. A layout is a matched set arranged for one piece, typically a necklace or bracelet, with each stone's position and size fixed.

Byrex supplies all of these to the trade. The core calibrated species are sapphire in blue, pink, yellow, teal and white, ruby, emerald, tsavorite, spinel, tourmaline, aquamarine and tanzanite, in rounds, ovals, cushions, pears, emerald cuts and princess cuts in the standard sizes, together with calibrated and matched diamonds.

Each parcel is filmed unedited so that a buyer can see the colour and the match before the goods are sent on approval. Treatment is stated for the lot. Where a buyer needs laboratory confirmation on a calibrated parcel, Byrex arranges reports on representative stones or on every stone, depending on the size and value.

Buying calibrated gemstones from Byrex Gems

Byrex Gems has been in Toronto since 1988, and more than seven thousand trade customers in Canada and abroad have bought from us. Many of our calibrated stones, matched pairs and layouts come with reports from leading laboratories where a stone warrants one; all of them are photographed in our office, unedited and unfiltered.

Approved trade buyers see prices online. Others may write at any hour: WhatsApp +1 (437) 450-3786 is answered within hours and email to info@byrex.com the same day, seven days a week. What is listed is a part of what we hold: more calibrated sizes, matched pairs and layouts are kept in the vault, and what we do not hold ourselves we can source through our offices worldwide. Private viewings are arranged by appointment in Toronto, Hong Kong, Bangkok and Dubai.

Calibrated Gemstones: questions buyers ask

Where can I buy calibrated gemstones in Toronto?

What does calibrated mean for a gemstone?

Cut to a standard millimetre size and shape, within a small tolerance, so the stone fits a ready-made mounting and repeats across a production run. Calibration refers to dimensions, not carat weight; the weight of a parcel is quoted as a total.

What tolerance should I expect on calibrated stones?

About a tenth of a millimetre on small rounds and slightly more on larger fancy shapes, but the figure should be agreed in advance. Depth is often the bigger variable, so ask for the parcel to be sorted for depth as well as outline when settings are tight.

Are calibrated sapphires and rubies heated?

Generally, yes. Calibrated corundum is mostly heated to bring the colour of a parcel together, and calibrated emerald is clarity-enhanced; the disclosure applies to the lot. Unheated parcels are available on request, sorted by the supplier and, where needed, confirmed by laboratory reports on sample stones.

How do I specify the colour I need?

Send a reference stone, a sample from a previous parcel or a photograph taken under known light, together with the setting style. Words such as medium blue mean different things to different sorters; a physical or photographic reference removes the guesswork and sets the match tolerance.

Does Byrex supply laboratory reports on calibrated parcels?

On request. Small calibrated goods are normally sold on the supplier's sorting and a stated treatment for the lot. Where a buyer needs confirmation, Byrex arranges reports from GIA, GRS, SSEF, Gübelin, Lotus or AGL on representative stones or on each stone, depending on size and value.

What sizes are hard to find in calibrated goods?

Fine colour above about 7 by 5 mm, because large rough is cut into single stones of the best weight rather than to a fixed size. Matched parcels of 10 by 8 mm sapphires or rubies in good colour are assembled to order and take time.

Does Byrex supply calibrated stones to designers and private clients?

Byrex supplies calibrated stones to the jewellery trade, including independent designers and bench jewellers, and receives private clients by appointment in Toronto. Prices are shown to approved trade buyers who sign in; private clients can view parcels and order through their jeweller or through Byrex.

Can I view calibrated parcels in Toronto?

Yes, by appointment at 27 Queen Street East, Suite 407, Toronto. Parcels are filmed unedited and can be examined under daylight-equivalent light with a gauge and loupe, so colour match, depth and tolerance can be checked before the goods go out on approval.

Byrex Gems, 27 Queen Street East, Suite 407, Toronto. Coloured gemstones and natural fancy colour diamonds for the trade since 1988, and for private clients by appointment.

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