One problem for making a traditional tennis bracelet is the calibration size of square gemstone or diamond. The most famous stone size is 2 mm. The problem that often occurs in this type of bracelet is that it set by using channel setting so the stones have to be exact size for the design unlike prong set that can varies a bit (from my experience about plus or minus 0.2 mm).
One time, I need to purchase blue sapphires for tennis bracelet order at the size of 2 mm. Before I was going to purchase the stone, I ask my staff what stone size for this type of setting. She said to me “2 mm”. So I prepared my sieve table and a sieve size measurement before I went to purchase. I made a sieve according to the table (+8,-8.5) for this specific size. After I purchased I brought back the stones but my staff said it did not fix the setting.
The problem turned out to be her sieve measurement was not calibrate as my device. Some other jewelry manufacturers who are serious with stone size calibration are routinely change their device every 6 months since the machine can become obsolete. For us, we use the more economical approach. So after this problem, each time I need to purchase calibration size stones, I need to calibrate my device to be the same measure as my staff device with a CZ stone.