Emerald is May’s traditional birthstone, but since good quality emerald is getting harder to find (I still say the most beautiful ones I ever saw were at the British museum in ancient jewelry) it seemed a good month to look at two other gorgeous green gems.
Especially since outside the spring greens are starting to ripen!
Chrome diopside really needs a trade name. Despite the fact that it sounds like a polishing agent, it is a beautiful green stone that is sometimes used as an emerald replacement.
The word diopside comes from Greek, meaning double shape, after the shape of its crystals. Chromium is the element that gives chrome diopside its name and color. Traces of chromium are also what make emeralds green. Oddly enough, it’s also what makes rubies red!
Chrome diopside can indicate proximity to diamond mines. So some people search for minute crystals as a hint of where to mine. Most chrome diopside come from Siberia, near the diamond mines there. It is also sometimes found near the diamond mines of South Africa.
It is a much softer stone than emerald. The hardness of stones is measured on the Mohs scale, and chrome diopside sits around 5.5-6.5. That means it is more easily scratched than emerald. It is best used in earrings and pendants; or in rings with a protective setting.
Emeralds are tougher. They are rated at 7.5-8 in the Mohs scale; but it is one of the few gemstones expected to have inclusions. Inclusions break up the crystal structure and make both visible and structural flaws.
(One of the things I love about emeralds is that even the best gems are expected to have flaws. Visible flaws in emeralds are called jardain, French for garden, for the foliage effect flaws add to the stone.)
Tourmaline sits between these two on the Mohs scale at 7-7.5. The name tourmaline covers a large group of related stone species that come in all different colors: clear, yellow, pink, red, brown, green, violet and black. Multicolored crystals are more common than single colored ones.
Originally a lot of the different stones each had their own name; For instance verdelite was the name given to all shades of green and indicolite for all shades of blue tourmaline. Now they’re mostly just referred to as green tourmaline or blue, etc.
One of the classic color combinations for tourmaline is the watermelon tourmaline: a crystal that’s green on the outside and shades to pink on the inside, so that the cross-section looks like a slice of melon. (I don’t actually like watermelon, but I’ll take a slice of watermelon tourmaline any time, thank you.)
The intense pink and green are normally the most desired tourmaline variants. The pinks range into the most delicious raspberry colors while the best greens can almost put emeralds to shame.
Tourmaline is found in many places all over the world. Brazil is the largest supplier, but mines are found on every continent except Antarctica. In the United States tourmaline is found in Maine and California, and is the former’s state stone.
* Care and feeding of chrome diopside- it’s light stable, so it won’t fade in sunlight like some other gems (yes, even natural ones) however, it is sensitive to heat and hydrofluoric acid, so pieces with chrome diopside shouldn’t be cleaned using a steam or ultrasonic cleaner