Blue Diamond turquoise is a trade name applied to high-grade turquoise recovered from the Blue Diamond mine in Esmeralda County, Nevada. The material is distinguished by an intense sky-blue to robin's-egg-blue colour, a relatively low matrix content, and a hardness that places it among the more durable natural turquoise available on the American market. Although Nevada is not the largest turquoise-producing state by volume, its deposits have long been regarded by collectors and Native American silversmiths as sources of some of the finest material on the continent, and Blue Diamond turquoise occupies a respected position within that tradition.

Geological Context

Turquoise forms as a secondary phosphate mineral, typically in arid regions where copper-bearing solutions percolate through aluminous host rock under oxidising conditions. The chemical formula is CuAl₆(PO₄)₄(OH)₈·4H₂O, and the characteristic blue colour arises from the presence of copper, while any greenish shift generally reflects a higher iron content or partial replacement of aluminium by iron. Esmeralda County sits within the Basin and Range physiographic province of the Great Basin, a geological setting that has proved highly productive for turquoise formation across Nevada. The specific host rock and hydrothermal history of the Blue Diamond deposit yield a material with relatively low iron content, which accounts for the clean, saturated blue tone that distinguishes it from greener Arizona or New Mexico material.

The hardness of Blue Diamond turquoise is reported in the range of approximately 5.5 to 6 on the Mohs scale — towards the upper end for natural American turquoise — which contributes to its suitability for jewellery use without stabilisation. Specific gravity typically falls between 2.60 and 2.85, consistent with well-consolidated natural turquoise.

Colour and Appearance

The most valued Blue Diamond material presents a uniform, medium-to-medium-dark blue with good saturation and minimal veining. The matrix, where present, tends to be fine and unobtrusive rather than the bold spider-web or black-matrix patterning associated with deposits such as Kingman in Arizona or Cerrillos in New Mexico. Collectors who prize clean, solid colour — sometimes called Persian-style turquoise in the trade, in reference to the historically celebrated Nishapur material from Iran — find Blue Diamond among the American sources most closely approaching that aesthetic ideal. Stones with a pronounced robin's-egg-blue tone and virtually no matrix command the highest premiums.

It should be noted that colour alone cannot identify a stone as Blue Diamond turquoise; gemmological origin determination for turquoise remains challenging, and no standard laboratory test reliably distinguishes one Nevada mine's production from another. Provenance documentation and chain of custody from a reputable dealer are therefore important considerations when purchasing material represented as Blue Diamond.

Production and Rarity

The Blue Diamond mine has produced limited quantities of gem-grade material over its operational history, and production has been intermittent. This scarcity is a defining commercial characteristic: unlike large-scale operations that supply stabilised turquoise to the mass market, the Blue Diamond deposit has never yielded the volumes necessary to support broad distribution. Fine, untreated Blue Diamond turquoise consequently appears infrequently on the market, and when it does, it tends to move quickly among specialist dealers, collectors, and Native American artists who work in the Navajo, Zuni, and other Southwestern silversmithing traditions.

Treatment Status and Value Implications

As with all turquoise, the treatment status of Blue Diamond material is central to its valuation. The industry recognises several categories:

• Natural (untreated): No impregnation, stabilisation, or colour enhancement. The rarest and most valuable category. Fine natural Blue Diamond turquoise in this category commands significant premiums.
• Stabilised: Porous or soft rough is consolidated by impregnation with a colourless resin or polymer under vacuum and pressure. Colour is not artificially altered, but the material is hardened to make it workable. Stabilised Blue Diamond material, if the rough is genuinely from the mine, retains some collector interest but is valued considerably lower than natural stones.
• Treated (colour-enhanced or dyed): Material whose colour has been artificially intensified or altered. This is the least valuable category and, when not disclosed, constitutes misrepresentation.

The American Gem Trade Association (AGTA) requires disclosure of all treatments, and reputable dealers working with Native American artists and collectors adhere to this standard. Buyers should request written disclosure of treatment status and, for significant purchases, consider requesting a report from a recognised gemmological laboratory, though it should be understood that laboratories can confirm treatment status more reliably than they can confirm specific mine origin for turquoise.

Nevada Turquoise in Broader Context

Nevada has historically been the most prolific turquoise-producing state in the United States, with notable deposits including Carico Lake, Royston, Lander Blue, Lone Mountain, and Number Eight, among others. Each deposit has a characteristic colour signature and matrix pattern that experienced traders learn to recognise, though formal scientific origin determination remains imprecise. Blue Diamond turquoise is positioned at the quality end of this spectrum, alongside Lander Blue — another Esmeralda County material — and the finest Lone Mountain production. The relatively clean blue and good hardness of Blue Diamond material make it particularly sought after by silversmiths who prefer to let the stone speak without heavy matrix distraction, and by collectors assembling reference suites of American turquoise by mine origin.

The broader Nevada turquoise market has been affected, as all natural turquoise markets have, by the prevalence of stabilised, simulated, and dyed material at lower price points. This makes documentation of natural, mine-specific material increasingly important for both commercial and cultural reasons, as Native American artists and their customers place high value on authenticity of material as well as craftsmanship.

In the Trade

Blue Diamond turquoise is traded primarily through specialist American turquoise dealers, at Southwestern jewellery shows such as the Tucson Gem and Mineral Show, and through auction houses handling Native American art and jewellery. Prices for fine, natural, untreated cabochons vary with size, colour saturation, and matrix character, but top-quality material consistently commands prices well above stabilised Nevada turquoise of comparable size. Collectors and jewellers acquiring Blue Diamond turquoise for significant use are advised to seek material with documented provenance and, where possible, independent confirmation of natural treatment status.

Further Reading

• GIA: Turquoise Quality Factors
• AGTA: Turquoise
• IGS: Turquoise Gemstone Information