Hastings' Dictionary of the Bible (1898)
SAP'PHIRE. T. It was certainly of a blue color. Ex 24:10; Eze 1:26; Dan 10:1. But it is generally agreed that the ordinary sapphire of the ancients was our lapis-lazuli, an opaque mineral of a dark azure hue. Some scholars still hold that the Bible references require a transparent, hard, and valuable gem like the true sapphire. This stone is next to the diamond in lustre, beauty, and hardness. It differs only in color from the Oriental ruby, varying from the deepest to the lightest blue, and even to pure white. See Stones, Precious.