The term solitaire does not refer to the stone but the setting. A solitaire setting contains one "solitary" stone. A solitaire can be any size stone.
I believe it is 900 Gold which makes it 21.6 carat.
A one carat diamond weighs one carat and contains one carat.
One carat is equal to 200 mg.
1 carat = 6.5 mm
.20 grams equal one carat.
One carat = 1/5th of a gram
One carat equals .20 grams.
1 carat is 0.2g, so 1/2 of a carat equates to a 0.1g gemstone.
1 grain is equal to 0.323 Carat (int) 1 carat (int) is equal to 3.086 Grain
each carat is 200 miligrams
22 carat of 2 gram = 140 dhs
Your figure 0.005 represents 005/100ths of a carat.