Opal vs Moonstone

How Opal and Moonstone differ in what they are, color, hardness and care.

Opal

	Opal	Moonstone
What it is	A gem whose play of color comes from tiny silica spheres that diffract light. Opals with this effect are called precious opals. Opal holds 3 to 21 percent water.	A feldspar gem known for adularescence, a floating glow that moves as you turn it.
Birthstone for	October	June
Colors	Rainbow play of color; Described by body color: black or white	White or colorless with a soft blue sheen (most common); Rainbow, with flashes of blue and other colors; Peach and gray
Mohs hardness	5 to 6.5	6 to 6.5
Toughness	Very poor to fair. Wear with care to avoid scratching or breaking it.	Poor. It has two cleavage directions, so a hard blow can break it; it is usually set in pendants, earrings and pins rather than rings.
Everyday wear	Delicate	Delicate
Ultrasonic cleaner	Not safe (GIA: warm soapy water is the only safe way)	Never
Main sources	Australia (about 95 percent of world supply since about 1850), Mexico, Brazil, Honduras	Not stated
Common treatments	Can be impregnated with oil, wax or plastic, or given sugar or smoke treatments.	Not stated

Choose by the color you love and how the piece will be worn; for a ring worn every day, the tougher stone will last better.