The National Association of Jewelers released a list of so-called “modern birthstones” in 1912 in the United States. Today there are several alternate birthstone lists, so you have some choice – traditional, modern, stones associated with your zodiac sign, etc.
Opals are a popular birthstone choice for April. Traditional birthstones for April are diamond, opal, and sapphire, but you can also consider rock crystal (quartz) or another white/clear stone like white topaz. Sun Signs and Star Signs will provide even more choices – amber, coral, rose quartz, azurite, and turquoise for Taurus and bloodstone for Aries.
People recognize opals by their characteristic play of rainbow like colors. You need to be careful with opals because opal is a relatively soft (5.5-6.5) stone and they are sensitive to pressure, hard knocks, heat. Opals are 3-30% water and they can dehydrate if stored under improper conditions.
There are several types of opal –
White opal is white or a very light color with char. color play
Black opal – precious opal with char color play – dark gray, dark blue, dark green, or dark gray black. Black opal is less common than white opal
Boulder opal-precious opal with a dark base and color play. It occurs as pebble rock where opal fills in hollows in another stone
Jelly opal is bluish-gray precious opal with minimal color play
Crystal opal transparent with strong color play on a colorless, vitreous (oily looking) surface
Harlequin opal – transparent to translucent precious opal with mosaic like colors patterns
Fire opal – orange color in matrix – very sensitive to any stress.
Common opal is opaque with no color play – also called Potch