Chrome Diopside is colored green because it contains Chromium. Chromium is the Latin name for the element also denoted CR on the periodic table of elements - element number 24. In French, the name is Chrome. Many gem names are taken from the French language -- but you'll notice that the name Chrome Diopside is not nearly as beautiful as some other gem names -- however, don't let that fool you because this gem is incredible.
The crystal structure of chromium is a cubic body centered. The diopside chemical formula is CaMgSi2O6. With Chrome Diopside, the diopside is rich in chromium. Therefore, the chemical formula is CaMg (Fe,Cr)Si2O6 (The iron binds with the Chromium into the mineral content.) There are other varieties of diopside; however, chrome diopside is the rich-green color gem graat.