Casting 18k gold

Hi, i am Raymond, i am newbee in casting gold and learn it by my self. I am trying to cast 18k yellow, white, and pink gold but I don’t know what composition to make those 18k alloy which is suitable for casting. Could somebody please help me on this. Thank you

Not a topic for this site, I am assuming, but to answer your question, a basic point, 18kt gold is 18 parts pure gold and 6 parts alloy (6+18=24k).
The alloys you use can vary, but any decent jewelry supplier can sell you the alloy to mix. like here:[Metals]
If this is for manufacturing or retail, you must get a great scale because accuracy is of utmost importance if selling a piece as 18k or 14k or whatever karat you will be working on. (In my youth, I owned a jewelry repair shop).

Thanks RC_Submarine,
Thanks for your explaination but i am not sure i can find alloy manufacture such as riogrande in my country. Thats why i am trying to make my own alloy