925 Sterling Silver is a combination of 92.5% pure silver and 7.5% of another metal, and it is the highest percentage of fine silver possible for jewelry subject to everyday wear. Fine silver (99.9% pure) is generally too soft and malleable for jewelry. Therefore, it is usually combined with copper to give it strength, while at the same time preserving both the ductility and beauty of its original form.
Oligoclase is a rock-forming mineral belonging to the plagioclase feldspars. The Mohs hardness is 6-6.5 and the specific gravity is 2.64-2.66. In color it is usually white, with shades of grey, green, or red.