Birthstones

Stick with the Standards Or Choose Your Own

- Kenneth H. Rohn

For as long as humans have been fascinated with precious gems, they have assigned special significance to them. The 12 zodiac gems formed the basis of the modern, Western birthstone list. The national trade association Jewelers of America (www. jewelers.org) established a list of birthstones in 1912 that remains the standard today. Alternative lists also exist, and who’s to say you can’t choose your own?

JANUARY

Garnet has been the birthstone for January since the 15th century, at least. With a Mohs hardness of 6.5 to 7.5, it can be faceted into beautiful gemstones that wear well in jewelry. Since the term “garnet” actually refers to a group of nesosilicate gems, those born in this month can choose from a rainbow of colors. The most common members are red almandine (iron-aluminum silicate), red pyrope (magnesium aluminum silicate), orange-yellow spessartine (manganese aluminum silicate), the yellow or green varieties of andradite (calcium-iron silicate), predominately green grossular (calcium-aluminum silicate), and rare, bright-green uvarovite (calcium chromium silicate).

FEBRUARY

From the 15th century to the present, amethyst has been the preferred birthstone for February. Amethyst belongs to a mineral family that can compete with garnet for diversity of color: quartz. Pure quartz is colorless, as exemplified by Herkimer diamonds. The causes of amethyst’s shades of pale violet to rich purple are radiation and the inclusion of iron impurities and trace elements. As a rule, amethyst crystals are short and stubby, and occur in large numbers, often filling a large vug a hollow petrified tree section, or lining the inside of a geode. Fine crystals that are large enough to produce a faceted gem of over 20 carats are rare.

MARCH