Amethyst 4mm Round - 8-Inch Rose Wood Sardonyx has a Sard base

Sardonyx has a Sard base

created when silica hardens within the fissures of other stones

orange and rust are due to traces of hematite within the stone

gray and mauve stone

Additionally

Amethyst 4mm Round - 8-Inch Rose Wood Sardonyx has a Sard baseAmethyst is a beautiful purple stone, known as a Gem of Fire by ancient cultures. It has been greatly sought after throughout history and was at times valued as highly as Diamond. Today, this semi precious variety of quartz is found in many locations around the world. The presence of Manganese within the stone produces the purple hue, and variation of the amount of iron in the stone creates a color range from reddish purple to deep violet to light