gem opal造句

• It consists of 99 % gem opal with an even colour throughout the stone, and has been left in a natural organic state, unpolished and uncut with blemishes.
• Although it has been reported that Northern African opal was used to make tools as early as 4000 BC, the first published report of gem opal from Ethiopia appeared in 1994, with the discovery of precious opal in the Menz Gishe District, North Shewa Province.