Abstract: The blue chalcedony is a special local gemstone in Taiwan Province.The blue chalcedony from Taiwan Province owes the beauty and popularity to its vivid blue—greenish blue colour and its value is the highest among the jade from Taiwan Province.It also outshines others in the world market. The blue chalcedony from Taiwan Province is found in the seacoast mountain range of the eastern Taiwan,and it belongs to hydrothermal deposit.The blue chalcedony from Taiwan Province is compared with its simulants in detail.Besides,the blue chalcedony diggings in Donghe village,Taidong county,is investigated for its distribution.Its attitude and origin are studied.The blue chalcedony samples are compared with its simulants in detail.