Nigerian Mint Green Beryl

Nigerian Mint Green Beryl are beautiful pastel bluish-green gemstones from the famous Gwantu deposit in Nigeria’s Kaduna State. Nigerian Mint Green Beryl’s magnificent and uniquely beautiful hues, combined with their brilliance, high transparency, everyday durability, and extreme rarity, make them an exceptional African jewel for the true gemstone connoisseur.

Hardness 7.5 – 8
Refractive Index 1.562 – 1.602
Relative Density 2.66 – 2.90
Enhancement None


Related to Aquamarine and Emerald, Nigerian Mint Green Beryl’s very attractive, bright and exceptional, pastel mints (60-70/30-40 percent bluish-greens) are a tremendously rare color for Nigerian Beryl. This combined with their beautiful brilliance and durability, makes them a popular and well-suited choice for gemstone jewelry.

Unlike Emeralds, Nigerian Mint Green Beryl has a high clarity and transparency, making color their most important consideration. As color is such an important gemstone value determinant, representing 50 percent of their value, skillful lapidaries employ cuts that accentuate color.

They are faceted to the highest lapidary standards for maximum brilliance, excellent proportions, and symmetry, with an eye-clean clarity, the highest quality clarity grade for colored gemstones.

Nigerian Mint Green Beryl is a member of the Beryl mineral family (from the ancient Greek ‘beryllos’, meaning blue-green stone), commonly known as the ‘mother of gemstones’ because of its highly regarded gem varieties. Pure Beryl is colorless and trace amounts of elements are responsible for producing Beryl’s wonderful colors. Apart from Nigerian Mint Green Beryl’s minty verdant hues, other Beryl gemstones include Aquamarine blues, Bixbite reds, Emerald greens, Goshenite whites (colorless), Heliodor greenish-yellows, and Morganite pinks.


Colored by trace amounts of iron, Green and Mint Beryl are predominately sourced from Catugi Três Barras in the Brazilian state of Minas Gerais (‘General Mines’ in English), the Jos Plateau in Nigeria’s Plateau State (discovered in the mid-80s), and from Gwantu in Nigeria’s Kaduna State (first unearthed in the 1980s, with new albeit limited discoveries reported in April 2011). Totally natural and unenhanced, Nigeria is the premier source, noting Brazilian ‘Green’ Beryl’ is enhanced for color and still being unearthed.

The source of our gems, Gwantu was once a prolific producer of excellent Mint Beryl but is now ostensibly depleted with only miniscule quantities of historically mined gems rarely available. Understandably, Nigerian Mint Green Beryl commands higher prices due to their entirely natural hues accentuating their extreme rarity.

Gwantu Beryl is typically found in vugs (a small cavity inside a rock), and is often associated with Aquamarine, Emerald, and Tourmaline. There is some controversy among ‘experts’ regarding this gem’s nomenclature. While Nigerian Beryl possesses three phase inclusions practically identical to Colombian Emerald, the absence of significant chromium or vanadium trace elements doesn’t make them green enough to earn the ‘Emerald’ moniker.

Although this and their level of saturation traditionally disqualifies them from being classified as Emerald, other experts disagree. For example, in her excellent book, ‘Ruby, Sapphire & Emerald Buying Guide’, Renée Newman states: “there is no agreed-upon criteria in the trade for distinguishing between Green Beryl and Emerald”. She favors keeping it simple for consumers, using ‘Emerald’ to refer “to all Beryl ranging from bluish green to yellowish green regardless of its tone, color purity or coloring agent”. While a sensible approach, there is typically a strict tone description required for Emerald. If it is not medium or darker many do not consider the gem Emerald. Instead they classify it as ‘Green Beryl’, ‘Mint Beryl’ or ‘Mint Green Beryl’.

While this might seem reasonable for practical purposes, scientifically the variety is defined by its coloring agent. Accordingly, the American Gemological Laboratory New York (AGL) recognizes any Green Beryl colored by chromium and/or vanadium as Emerald regardless of the tone. Almost all Emeralds contain iron as a trace element, though the amount may change from one formation to another. A Beryl variety that owes its green color to iron is typically named Green, Mint or Mint-Green Beryl.

Durability & Care

Nigeran Mint Green Beryl (Mohs’ Hardness: 7.5 – 8) is an excellent choice for everyday jewelry. Always store Nigeran Mint Beryl carefully to avoid scuffs and scratches. Clean with gentle soap and lukewarm water, scrubbing behind the gem with a very soft toothbrush as necessary. After cleaning, pat dry with a soft towel or chamois cloth.

Map Location

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