Common opal is opal without the famous rainbow flash, and it is anything but boring. It is hydrated silica, the same material as precious opal, but its internal structure is too irregular to split light into play-of-colour. Instead it comes in lovely solid shades: pink opal from Peru, blue opal from Peru and Oregon, green, yellow and milky white from many places. It often has a soft, almost porcelain-like glow that suits modern, minimal jewellery beautifully.
Common opal sits around 5.5 to 6 on the Mohs scale and contains water, so it appreciates gentle treatment. Keep it away from prolonged heat, harsh chemicals and ultrasonic cleaners, and store it somewhere it will not get scratched by harder stones. It is cut as cabochons and beads, and it is lovely in pendants and earrings. Pink opal in particular has look-alikes, including dyed material and phosphosiderite, so buy from a seller who knows the difference. A soft, damp cloth is all it needs for cleaning.
Same mineral as precious opal, minus the colour play.
