How many kilograms of ruby's are there in 5.8 carats? Just divide by 5000 to get the answer of 0.00116 kilograms.
In 8.3 carats of gold there are 0.00166 kilograms, to achieve this take 8.3 and just divide by 5000.
To convert 6.8 carats into kilograms divide by 5000 giving 0.00136 kilograms.