Introduction to Chrysoberyl Chrysoberyl is an aluminate of beryllium with the specifications BeAl2O4. The name chrysoberyl is derived from the Greek words chrysos and beryllos, meaning “”a gold-white spar””. Notwithstanding the comparison of their names, chrysoberyl and beryl are two entirely distinct gemstones, although they both contain beryllium. Chrysoberyl is the third-hardest frequently faced natural gemstone and lies at 8.5 on the Mohs scale of mineral hardness, between corundum and topaz. An exciting feature of its crystals is the cyclic twins called trillings. These twinned crystals have a hexagonal fitness but are the outcome of a triplet of twins with each “”twin”” oriented at 120° to its acquaintances and taking up 120° of the cyclic trilling. If only two of the three permissible twin adjustments are present, a “”V””-shaped twin results. Normal chrysoberyl is yellowish-green and permeable to translucent. When the mineral displays good pale green to yellow color and is transparent, then it is used as a gemstone. The three main varieties of chrysoberyl are ordinary yellow-to-green chrysoberyl, cat’s eye or cymophane, and alexandrite. Yellow-green chrysoberyl was referred to as “”chrysolite”” during the Victorian and Edwardian eras, which confused considering that name has also been used for the mineral olivine (“”peridot”” as a gemstone); that name is no longer used in the gemological taxonomy.