A Treatise on Diamonds, and Precious Stones/Chapter 2/Section 3
SECT. III.
On the Ruby—Spinelle and Balais.
The Spinelle, when perfect, is a gem of great value and scarcity; its color is a fine, full carmine or rose red, which varies in intensity; in hardness and specific gravity it is inferior to the oriental ruby, and it differs also in some other characters, which will be described in the Appendix.
It is found in Ceylon and Pegu, of an octahedral form. Small crystals, from one to two grains, are very common, but stones of three carats and upwards are rare, and may be considered nearly of equal value with the oriental ruby.
BALAIS RUBY.
This is a pale variety of the spinelle; it varies in color from light red to yellowish red. It probably derives its name from some supposed locality, or from some peculiar earth, in which it may have occurred.
The Balais possesses considerable beauty, and though not so rare as the spinelle, it is by no means common. It is much admired for its agreeable tinge of color, and, when pure and perfect, sells for a high price, but considerably less than the other distinguished stones of this class.