Vietnamese Star Rubies
Yen Bai Province in northern Vietnam is widely known for producing rubies and sapphires. Of the rubies and sapphires mined, roughly 10–15% are gem quality, while the rest are used as carving material or as specimens. Much of Yen Bai's production comes from the Tan Huong–Truc Lau area, which is known for producing cabochon-quality gems that can be polished to display sharp, attractive stars – an optical phenomenon called asterism. The asterism is typically caused by light reflecting off rutile inclusions. The star rubies seen here (weighing 6.16 carat to 11.66 carat) are from Tan Huong–Truc Lau.