Many years ago, I had the privilege to learn and practice with some of the historic tools used for gem measurements (amongst others).
One of those tools was a balance scale.., before the invention of the electronic scale, gem professionals used a manual balance to figure out the carat weight of gems and diamonds.
It consisted of two small bowls suspended on chains at equal distances from a fulcrum, on one bowl side the gems were placed and on the other bowl we would slowly add tiny weight elements each representative of a specific weight mass until the scale balanced out.
Then we would need to count the weights which represented the carat weight of the gem or diamond.
This manual fashion discovering the weight of a gem added some real excitement to the process…, the “slow revealing” which is missing from so many things in todays instant world.
The three antique Colombian emeralds in this picture are resting on one such antique balance scale which my late father actually utilized and also taught me how to use. The three knobbed metal saucers or disks surrounding the emeralds are the tiny weights used for the process.
If we look carefully we are able to notice the catalogued carat weight no. on two of them, although they are upside down, the left disk marks a 10 C for ten carat, the right disk is a 5 C for five carats, and the smaller (out of focus) is a 1 C for one carat.
What is wonderful about these weight saucers is the fact that the larger ones also played role as a lids. Uncovering the lids would reveal small compartments holding tiny aluminum flakes which were used for under carat weight fragments. Those usually consisted of ½ ct down to 0.05ct for a precise weight measurement.