To convert carats to kilogrammes divide by 5000. I've generated some hopefully helpful examples randomly below, as with most random sentences please excuse the repetitive and occasionally comic outcomes.
To convert 0.8 carats into kilogrammes divide by 5000 giving 0.00016 kilogrammes.
In 9.4 carats of ruby's there are 0.00188 kilogrammes, to achieve this take 9.4 and just divide by 5000.
How many kilogrammes of silver are there in 7.8 carats? Just divide by 5000 to get the answer of 0.00156 kilogrammes.
You've got 4.1 carats of platinum but someone only wants to buy that in units of kilogrammes, to change the units divide by 5000. Now you have 0.00082 kilogrammes.
You have 4.5 carats of gold but you need to know how many kilogrammes that is. To get the answer divide by 5000 which gives you 0.0009 kilogrammes.