semiprecious stone[sĕmˌē-prĕshˈəs, sĕmˌī-]
The American Heritage® Dictionary of the English Language, 4th edition Copyright © 2010 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
A gem, such as an opal, that has commercial value but is not as rare or expensive as a precious stone.