The following karat markings found on jewelry would usually indicate it is gold.

For 10 karat -	10k, 10kt, 416
For 14 karat -	14k, 14kt, 585
For 18 karat-	18k, 18kt, 750

Any of the following markings found on jewelry would indicate a gold content of little value and would not be a good candidate to sell as scrap gold. Pyrite is often referred to as "fool's gold" and caused many early pioneers to incorrectly beleive they had discovered gold.  Gold jewelry is nmot made from pyrite so should not be of concern when evaluating various types of jeweley. 

1/10, 1/20, GF, GP, GEP, RGP, Gold Filled

As a Hillsborough Jeweler we will perform a scrape test to help determine the authenticity of of a given peice of jewelry.  Sometimes a better gold test will be to cut the jewelry with a file to insure it is not simply gold plated.  We always ask permission before doing so as we want to be sure the item is definitely heading for melt and going to be worn.