Jacinth is really another form of the word hyacinth. It is used, now, especially to denote a reddish orange variety of zircon. The jacinth was a favorite jewel of ancient times, its mention ranging from the Bible to the Thousand and One Nights.
Jade
Two silicates of lime and magnesium are called jade. One, the true jade, is a complex silicate also called jadeite. It is a tough substance, usually green or white, and somewhat translucent. The other, less valuable form, called nephrite, occurs in other colors.
Found in Burma and India, also in Mexico and Central America, jade did not enter early into western literature; English mentions of jade usually refer to the horse.
The word jade is from the Spanish piedra de yjada, stone of the side. It is named from the belief that the stone counteracted pains in the sides and kidneys. And the word nephrite is from Greek nephros, kidney. Chinese women, indeed, clutched a piece of jade tightly in their hands during childbirth. They had a double purpose in this: the stone, being an effective charm, lessened their labor pains; and, being a symbol of aristocracy, it ensured the male infant high rank and the female a successful marriage. Mandarins, though not for the same reasons, sometimes “spiked” their rice wine with powdered jade.
A piece of the deep green stone called imperial jade is one of the most beautiful stones to look upon, and one of the most pleasant to touch. It combines superbly with diamonds to create handsome jewels.
Jasper
Jasper was a stone treasured in antiquity. Although Biblical references indicate a greenish stone, the jasper we know today is usually reddish, yellow, or brown, in mottled colors. It is an opaque variety of quartz.
The jasper was sometimes used as a symbol of perfection. Thus the Scot poet William Dunbar, about 1525, hailed the growing capital of England:
London, thou art the flower of cities all!