Webster, Robert. <br/><br/>
Gems :  their sources, descriptions and indentification / 
Robert Webster. 
 - 4th ed. / 
 - London :  Butterworths,  1983. 
 - xxii, 1006 p. : ill. (some col.). 
<br/><br/><label>ISBN: </label>0408011483 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Precious stones.<br/>Gems.