From Wikipedia: "A blue chip stock is the stock of a well-established company having stable earnings and no extensive liabilities. Blue chip stocks pay regular dividends, even when business is faring worse than usual. The term is derived from casinos, where blue chips represent the greatest value among the many colors of chips."
Sapphire is hella expensive and always will be, therefore it is blue chip. Dynastic Hero US is also "blue chip", but Sapphire is a better game. Sapphire is the best blue chip game, IMO. Everything more valuable is less fun.
Possible exception: Bazaru de Gozaru.