demand
for them varying, cause also a change in the value at different times
attributed to them. We shall, therefore, following the example of many
other writers, adopt the alphabetical order* as the most simple,
convenient, and useful to those who wish to study this subject,
although perhaps it is the least scientific in a mineralogical point of
view. But we wish it to be understood that this work is not a strictly
scientific treatise so much as a collection of useful and curious notes
about all sorts of precious stones.
* This order cannot be observed in the translation, the initial letters of some gems being different in English.
