Ruby is the most expensive among all corundum gems because it contains chromium (كر, الكروم), because the output of ruby is very small. بالمقارنة مع الياقوت, the output is only 1/5 من ذلك الياقوت; and ruby is usually very crystallized. There are not many rubies larger than 5 قيراط. Rubies larger than 10 قيراط [...]
