184

Specific gravity, 23-37, 114

Sphene, 9, 62, 64

Spinels, 71, 90, 123, 140, 158, 188

Spodumene, 95, 170, 195

Star stones, 44, 46, 157

"Step cut" stones, 235

Structure of pearls, 258

Table, of hardness, 54

Table of refraction, 12-13

Table of specific gravity, 29

Tariff laws, 294-299

Test for double refraction, 10

Testing hardness, 51-54, 58

Testing imitations of pearls, 281

Testing unknown gems, 109-118

Tiger's-eye, 45, 138, 171

Topaz, 67, 73, 91, 124, 145, 159, 189

Toughness in stones, 119

Tourmaline, 72, 77, 79-81, 96, 146, 167, 194

"Triplets," 79, 246

Turquoise, 130, 148, 198

Unit of weight, 289

Variscite, 148

Vitreous luster, 41

Wearing qualities of gems, 119

Zircon, 9, 62, 72, 92, 97, 125, 147, 166, 191

Diamonds

A Study of the Factors that Govern
their Value

By

Frank B. Wade

"I shall speak a little more of the diamonds, that they who know them
not may not be deceived by chapmen who go through the country selling
them, for whoever will buy the diamond, it is needful that he know
them, ..."--Chap. XIV., _The Voyages and Travels of Sir John Maundeville_.

_Table of Contents_

I.--Colour.
II.--Flaws.
III.--"Make."
IV.--Repairing and Recutting.
V.--Mounting.
VI.--Buying the Engagement Ring.

* * * * *

G. P. Putnam's Sons

New York London

A Book of Precious Stones

The Identification of Gems and Gem Minerals and an
Account of Their Scientific, Commercial,
Artistic, and Historical Aspects

By Julius Wodiska

_8vo. With 33 Full-page Illustrations and 4 Colored Plates_

A description, in altogether a new fashion, of gems and gem minerals,
their nature and history, comprehensible to every reader, and of prime
value to students and to jewelers.

The general reader will enjoy the simple descriptions of the origin,
development, and treatment of the diamond, sapphire, and ot