Best loupe, caliper and wires to check sapphire, ruby and emerald beads
Bring a 10x triplet loupe, a metric digital caliper that reads to hundredths of a millimeter, and short pieces of the exact stringing materials you use: your thinnest and your standard beading wire or cord, a fine needle pre-threaded with your usual thread, and a couple of your regular headpins or eye pins. Use them to check drill quality, bead size and facet finish in under two minutes.