Brewer's: Precious Stones
(1) Each month, according to the Poles, is under the influence of a precious stone:
(2) In relation to the signs of the Zodiac:-
(3) In relation to the planets.-
The ancients divided precious stones into male and female. The darker stones were called the male, and the light ones were called the females. Male sapphires approach indigo in colour, but the female ones are sky-blue. Theophartos mentions the distinction.