blue chip

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A stock that sells at a high price because of public confidence in its long record of steady earnings.
• noun An extremely valuable asset or property.
• noun Games A blue poker chip of high value.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A high value gaming chip.
• noun A stock or other investment that has a high price because of its perceived reliability.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a common stock of a nationally known company whose value and dividends are reliable; typically have high price and low yield
• noun a blue poker chip with the highest value