Assay Hallmarking Rules and Guidlines

Any item of sterling silver 925 jewellery that is in excess of 7.78 grams by law has to be sent to an independent registered Assay Office for testing and hallmarking.
Any item under 7.78 grams it is legally OK to just mark 925 myself
For clarity providing a quick 3 or 5 day turnaround is only possible if I have blanks in stock that have already been sent for hallmarking.
As I am a fledgling business keeping thousands of pounds of hallmarked stock is not viable.
Hallmarking can take up to two weeks, posting to and from Sheffield, and increases the cost price of manufacturing by appx £10.00 per ring.