Sterling silver, 22K gold, Fossilized wood, sapphires: These are amazing stones!! Actually referred to as "Opalwood", what they are is chunks of fossilized or petrified wood, that have been replaced by silica over millions of years, causing these amazing patterns and colors. They are rare and getting harder to find really nice pieces. Prong set so you can the see the back as well. (I have been hoarding my few pairs of these stones for years….sadly I had to make myself make something from them!!) They are hanging from faceted rich brown silky sapphires. Bottom is 3/4" wide by 2-3/4" long from the post.