How to make gst bill for gold labour charges

sir i am also goldsmith .if u sent u r email id then i sent gold labour bill format

vnandaniya @ gmail.

+91 9924251885

Plz guide kijiye yee making charge ya labour pe gst kitna hai.. it's very confusing.. kahi see sahi knowledge hi nahi mil rahi.... 20 gm ka item bana .... 20gm *rate + making charge +3% gst ..... I'm registered jeweller .. Kya making charge per bhi koi additional tax lagana hai.... according to gst law