Gemstone Glossary

Heliodor

Appearing in yellow, yellow-green, orange, and brown colors, Heliodor is the yellow variety of beryl, the "mother of gemstones". Heliodor does not include golden colors that are aptly given the name of golden beryl.

Occurring in a variety if colors, all transparent beryl varieties are used as gemstones. Interestingly, pure beryl is colorless, with traces of different impurities being responsible for this gemstone's great color range. Gemstone color varieties that belong to beryl with specific names are emerald, morganite, goshenite, bixbite and aquamarine, with other colors of beryl being simply referred to by their color (i.e. golden beryl and red beryl etc.). Interestingly, all the variety names are generally accepted, except for Bixbite, which is not recognized by some authorities.

Available as faceted gems and as Heliodor Cats Eye, Heliodor has a hardness of 7.5 - 8, a refractive index of 1.57 - 1.60, a hexagonal crystal system, a weak pleochronic and a poor one directional cleavage. Beryl (Heliodor) is famous for their perfect, six-sided prismatic hexagon crystals that usually occur individually. These are often enormous and some 30-foot (8 meter), well-crystallized examples are known to have existed.


As treating the stone with oil can mask internal flaws in Heliodor, one must beware of unscrupulous dealers who will often apply this treatment to a stone without informing the buyer. All beryl varieties (including Heliodor) can be faceted into various gem cuts, and some stones display asterism and cat's eye effect when cut and polished into cabochons. Massive chunks of transparent beryl, usually morganite and Heliodor are sometimes carved into ornamental figures. Furthermore, perfect, transparent, six-sided crystals are occasionally worn uncut as Heliodor Rough necklace pendants.

Heliodor is found in Madagascar, Brazil, North Carolina and California in the U.S., in Rangkul, Tien-Shan Mountains, Tajikistan and Middle Eastern countries.