cending order of size as suggested
above) then write down the total, and on removing the weights count
aloud as they are replaced in the box and note if the total checks that
which was written down. It may seem unnecessary to be so careful in this
matter, but it is better to be over-careful than to make a mistake where
every hundredth of a carat may mean from one to five or six dollars or
more. No dealer can afford to have a stone that he has sold prove to be
lighter than he has stated it to be. One should be at least within one
one-hundredth of a carat of the correct weight.

It should be unnecessary to add that accurate weights _should never be
handled with the fingers_. Ivory tipped forceps are best for handling
the weights. The forceps commonly used for handling diamonds will, in
time, wear away the weights by scratching them so that they will weigh
materially less. Unless the weights are of platinum or plated with
gold, the perspiration of the hands would cause them to oxidize and gain
in weight. It would be well to discard the smaller weights, which are
most in use, every few years and obtain new and accurate ones. In case
this is not done one should at least have the weights checked against
others known to be of standard weight. Any chemist will have balances
and weights far more accurate than the best in use for precious stones
and will gladly check the weights of a gem dealer for a moderate fee.

To check the accuracy of your balance, change the stone and weights to
opposite pans, in which case they should still balance.

One should never overload a balance, both because the balance might be
injured and because the relative accuracy decreases as the load
increases. If the weight of a parcel of stones heavier than the total of
the weights provided with the balance is desired, the parcel should be
divided and weighed in parts.

While many dealers neglect some of the precautions above suggested and
somehow get along, yet it is safer to use care and to have correct
technique in the handling of one's balances.

Having indicated a few of the refinements of method in weighing we will
next consider the unit of weight in use for precious stones and see how
it is related to other units of weight and in what manner it is
subdivided.

THE UNIT OF WEIGHT FOR PRECIOUS STONES. The present unit for precious
stones in the United States is the _metric carat_. Most of the more
progressive countries have in recent years agre