What you normally see .925 which is the standard for Sterling silver, meaning the silver content in the piece is 92.5% (i.e., the remaining 7.5% is comprised of other elements).
.929 then could mean that the silver content in a piece is 92.9%.
Check out this online encyclopedia of silver marks, hallmarks & makers' marks.
Silver is a precious metal and, much like gold, is too fine to be utilized in its pure form.
To make silver durable enough for use in jewelry, pure silver, which has a .999 fineness (99.9%), is often alloyed with small quantities of copper (7.5%). The copper is added to strengthen the silver and the resulting product is .925 sterling silver (92.5%). Acceptable quality marks for sterling silver include: sterling, sterling silver, ster, and .925
Learn everything you need to know about silver on JewelryInfoPlace.com.
When buying for a jewelry, never act like this is your first—or even fifteenth—time in a jewelry store. If you seem like you’re in the know, if you come off as someone who’s in the business, most jewelers will be hesitant to try to dupe you. Find out how to buy jewelry like a jeweler at Vice.com.