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Natural Blue Diamonds

A natural blue diamond is a diamond coloured by trace amounts of boron in its crystal lattice, classified as type IIb and graded as a fancy colour at any strength. Blue is one of the rarest colours in diamond, and most blues carry a grey modifier; a pure, saturated blue is exceptional. Byrex Gems offers natural blue diamonds to the trade from Toronto, each with a GIA report confirming natural colour and filmed unedited, with prices shown to approved buyers and viewings by appointment.

Where to buy natural blue diamonds in Toronto

Byrex Gems lists 16 natural blue diamonds online today. 16 of them come with a report from laboratories including GIA. 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.

What is a natural blue diamond?

Blue in diamond comes from boron. A few boron atoms per million carbon atoms absorb red light and leave blue, and because boron also lets the lattice carry a charge, type IIb blue diamonds conduct electricity, a property no other diamond colour shares. The same stones often contain almost no nitrogen, which is why they are classed as type II, and many phosphoresce after exposure to ultraviolet light; the Hope Diamond's red afterglow is the best known example.

Boron reaches diamond only in a few places. The Cullinan mine in South Africa, called Premier until 2003, is the main source of blue diamonds and has produced most of the important blues of the past century. The historic Golconda mines of India produced the blues of the old royal collections, including the rough that became the Hope. Occasional blues have come from Botswana, Sierra Leone and Brazil.

A second, much rarer kind of blue is not caused by boron at all. Argyle produced a small number of violet and blue-violet stones associated with hydrogen, which it graded as blue violet. On a GIA report these are described by hue like any other stone, and the type is noted where tested.

How GIA grades blue diamonds

GIA grades blue on the fancy colour scale from Faint through Very Light, Light, Fancy Light, Fancy, Fancy Intense and Fancy Vivid, with Fancy Deep and Fancy Dark for darker tones. Blue is a fancy colour from the first step, so a blue diamond never carries a D to Z letter grade.

Most blues carry a grey modifier. Grayish blue, gray-blue and greenish blue all appear in GIA wording, and the last hue named is the dominant one: a grayish blue is a blue with a touch of grey, a blue-gray is a grey stone. A report that reads Fancy Intense Blue or Fancy Vivid Blue with no modifier is a pure blue, and in this hue pure wording is rare enough that it changes the class of the stone.

The colour origin line is decisive for blue. Irradiation can give a diamond a blue to blue-green colour, and such stones are usually nitrogen-bearing type Ia diamonds rather than type IIb; laboratories detect treatment by inclusions, spectra and trace-element chemistry, and the report states it. Laboratory-grown blue diamonds, also boron-doped and type IIb, are identified by their growth features. Any treatment must be disclosed at every sale.

What a jeweller should check before buying

Verify the report with GIA and match the inscription before anything else, because blue is the colour most often created by treatment or grown in a laboratory. Read the colour origin line and check whether the report notes type IIb.

Then look at the colour as it will arrive. Blues are graded viewed from the top, and most of them are light: a Fancy Light grayish blue is a typical stock stone, and it will look like a pale steel blue rather than the saturated colour of auction photographs. Decide whether the grey modifier is acceptable for the piece; in a halo of white diamonds a grayish blue can look near-colourless, while against white metal alone it reads clearly blue. Byrex films every blue unedited so the modifier can be judged honestly.

Cut matters. Cushion, radiant, pear and oval shapes hold blue; rounds and emerald cuts show the body colour plainly and are less forgiving of a light grade. Clarity in type IIb stones is often high, and buyers expect VS or better in anything above a carat. Pairs in blue are rare and are matched on tone and modifier before size, since two Fancy Light blues can differ visibly in grey.

What drives the value of a blue diamond

Saturation and purity set the tiers. A Fancy Vivid blue is one of the scarcest grades in any hue, and Fancy Intense blue follows at a distance. Below that, Fancy, Fancy Light and Light blues form the working market, and here the modifier matters most: a pure blue in any grade leads, a grayish blue is valued below it, and a blue-gray or gray-blue is judged as a grey stone with a blue cast.

Size multiplies rarity faster in blue than in any colour except red. Blues above one carat with Fancy or stronger colour are uncommon, and Fancy Vivid blues above a few carats are auction stones that set records when they appear. Value climbs in steps at the weights buyers search for.

Clarity carries more weight in blue than in pink or yellow, because type IIb stones are often clean and buyers expect it. Cut quality, fluorescence and phosphorescence are noted, and a documented type IIb classification with natural colour origin is itself part of the value, since it rules out treatment. Byrex shows full trade prices to approved accounts, offers larger blues on request and does not publish prices.

Famous blue diamonds and natural versus irradiated

The Hope Diamond, graded by GIA as Fancy Deep grayish blue and classed as type IIb, came from the Golconda region of India and has been in the Smithsonian Institution since Harry Winston gave it in 1958. The Oppenheimer Blue, a Fancy Vivid blue in an emerald cut, was sold at auction in Geneva in 2016. The Blue Moon of Josephine, a Fancy Vivid blue cushion cut from a rough found at Cullinan in 2014, was sold at auction in Geneva in 2015. Cullinan continues to produce a few important blues each decade, which is why its name appears so often in this list.

The category also has a look-alike problem. Irradiated blue diamonds have been produced since the mid-twentieth century; they are usually nitrogen-bearing type Ia stones, their colour often tends toward blue-green, and they do not conduct electricity. Laboratory-grown blue diamonds are type IIb like natural blues, but their growth structure identifies them. Neither is a natural blue diamond, both must be disclosed, and a GIA report stating natural colour origin and type IIb is the document that settles the question. Byrex offers only natural blues and quotes the report wording on every stone page.

Buying blue diamonds from Byrex Gems

Byrex Gems has served the jewellery trade from Toronto since 1988, and more than seven thousand jewellers, designers and dealers have bought from us in that time, some of them for decades. Many of our blue diamonds carry reports from GIA and other leading laboratories, and every stone is filmed in our office, unedited, so what you see is what arrives.

Approved trade buyers see prices online. A message on WhatsApp at +1 (437) 450-3786 is answered within hours; an email to info@byrex.com, the same day, seven days a week. What is listed is a part of what we hold: more blue diamonds 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.

Natural Blue Diamonds: questions buyers ask

What makes a natural blue diamond blue?

Boron. A few atoms of boron in the carbon lattice absorb red light and leave blue, and they also make the stone electrically conductive. Such diamonds are classed as type IIb, which is the signature of a natural boron blue.

Are most blue diamonds grey?

Most carry a grey modifier, yes. GIA wording such as grayish blue is common, and a pure blue with no modifier is scarce. The last hue named is dominant, so a grayish blue is still a blue diamond.

How can I tell a natural blue from a treated one?

By the laboratory report. GIA states colour origin and, for blues, usually the diamond type; natural boron blues are type IIb and conductive, while irradiated blues are usually type Ia. Laboratories detect treatment by spectra and inclusions.

Do Byrex blue diamonds have GIA reports?

Yes. Every natural blue diamond Byrex offers carries a GIA report confirming natural colour origin, and the report wording, including any note on type IIb, is quoted on the stone page.

Does Byrex sell blue diamonds to private clients?

Yes. Byrex sells first to jewellers and designers, but private clients are welcome by appointment at 27 Queen Street East in Toronto, where blues can be seen in person and reserved for a jeweller to set.

Can Byrex source a larger blue diamond?

Often, yes. Blues above a carat with strong colour are scarce, but Byrex sources them through contacts in Antwerp, Hong Kong, New York and South Africa, always with a GIA report confirming natural colour.

Can I view blue diamonds in Toronto before buying?

Yes. Viewings are by appointment at 27 Queen Street East, Suite 407, Toronto. The grey modifier in a light blue is best judged in person, under daylight-equivalent light and next to white diamonds.

Which metal suits a blue diamond?

Platinum or white gold. White metal lets a light or grayish blue read as blue, while yellow gold reflects into the stone and pushes it toward green. A white diamond halo can make a pale blue look lighter, so test it first.

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