Gem of the Month

Each month this section will feature either a topic of interest to gem lovers or one special gemstone with background on the material and its value.

Go to: Homepage -- what's new at ACS -- monthly specials and discounts -- "buried treasures" -- BWS/FS jewelry designs -- gem topic of the month -- gem topic archive -- birthstones -- ask Barbara -- key to all the codes used on the ACS site -- definitions of terms used on the ACS site -- how to order -- about ACS -- setting these gems -- free gemology course

 

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Golden Beryl

Beryl that is slightly greenish yellow, yellow, or orangey yellow is variously called heliodor, yellow beryl or golden beryl. These names might have originally been used to specify the particular color range, but I find that currently they are used indisciminantly and randomly, so I'm just going to pick one: golden beryl, and stick with it. Whatever it's called, this lovely gem has often been overlooked as its rarer and more expensive cousins in the beryl family (emerald, aquamarine and red beryl) have gotten most of the attention.

[Golden beryl gems showing a range of colors and faceting styles]

Like all beryls, golden beryl has a hardness between 7.5 and 8 and virtually no cleavage, which makes it an excellent jewelry stone, even for ring or bracelet use. Likewise, it shares the lovely brilliance and luster which clean, well cut members of this gem family are noted for. Since the rough for golden beryl is available in relatively large, clean pieces at good prices, facetors and carvers often use it for fancy cuts or carvings.

[Fancy cut golden beryls: checker top, buff top concaved cuts, concave faceted cut]

It is found primarily in granitic rocks, especially pegmatites in such locales as Russia, Brazil, Afghanistan and Madagascar. The pure mineral beryl is colorless. When slight impurities of oxidized iron are present in the crystal lattice, a yellow color is imparted (reduced iron, interestingly makes the color blue as in aquamarine). Although most of the golden beryl on the market is reasonably clean (as opposed to most emerald), it may have hollow tube-like inclusions which are quite typical for the entire beryl family.

[Heliodor crystal cluster: Image courtesy of www.mineralminers.com]

As supplies are widespread and reasonably inexpensive, there is little incentive to produce synthetic golden beryl, although it is certainly technically possible to do so. As far as enhancements, the story is about the same. It is possible to irradiate colorless beryl to produce a stable yellow color, but economically, it makes little sense to do so. As a result, enhanced pieces are probably the exception rather than the rule. Ethical dealers however, realizing that treatment by irradiation is undetectable may label specimens as [Gec: E] or [Gec: R], if they do not have compelling reason to assert the stone is positively untreated. Heating is not a useful treatment for this gem as it tends to remove the golden color, though often pieces are seen that are mislabeled as heated.
Care for gems of this type couldn't be easier, the only precautions would be the generic ones: avoid ultrasonic cleaners (if the stone is included) and store stones so that they aren't in direct contact with other gems which they might scratch or be scratched by.
It's high time for every gem lover to give this golden beauty a chance!

Value Considerations
With supplies being abundant this is one of the least expensive members of the beryl family (only colorless Goshenite commonly sells for less). As crystals are often relatively large and clean this means a sizeable, clean, well colored specimen can be had for a reasonable price compared to many gems. In general the price of golden beryl does not exponentially increase with size. The chief value considerations are then, depth and saturation of color and the desirability of the cut. You will see fancy cuts like concaved or carved pavilions in many specimens. To an extent, color is a personal preference, with some buyers choosing the purer yellows and others selecting the greener or more golden tones. Nonetheless, whatever the color, increased intensity of that color leads to an increase in gem value.
Gemological Properties:
Makeup: Beryllium, Aluminum Silicate
Crystal System: Hexagonal
Hardness: 7.5 - 8
Toughness: Good
RI: 1.57-1.58
SG: 2.80
Dispersion: 0.014 (low)
Cleavage: rare
Fluorescence: inert
Luster: Vitreous


Stones Currently Available:

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Go to: Homepage -- what's new at ACS -- monthly specials and discounts -- "buried treasures" -- BWS/FS jewelry designs -- gem topic of the month -- gem topic archive -- birthstones -- ask Barbara -- key to all the codes used on the ACS site -- definitions of terms used on the ACS site -- how to order -- about ACS -- setting these gems -- free gemology course