Wastage
An extra percentage added to the gold weight to cover metal lost during manufacture. Often charged even when no metal is lost.
Traditionally, cutting, filing and polishing lost a little gold, and wastage compensated the maker for it.
Modern manufacturing recovers nearly all of that dust, so wastage now functions as a second making charge under an older name.
It is usually quoted as a percentage of gold weight, commonly between 2% and 10%, and it appears before making charges on the bill.
When you are buying
Ask whether wastage and making charges are both being applied. Being charged twice for the same labour under two names is common, and pointing it out politely often removes one of them.
Making Charges
What you pay for craftsmanship on top of the metal, charged either per gram or as a percentage.
Gold Rate
The day's price of gold per gram at a stated purity. The base every gold bill is built on.
Buyback
What a jeweller will pay to take a piece back. Almost always based on metal content alone.