Silver-filled, like gold-filled, consists of precious metal (sterling silver or fine silver) bonded onto a base metal substrate (a red brass alloy, CDA#220).
The 1/20 and 1/10 notation refers to the ratio of sterling to brass core by weight, which is 5% and 10%, respectively.
* The value of siver-filled is greater than silver-plated because silver-filled has an actual layer of sterling silver, not just a microscopic film.
* Silver-filled jewelry is economical. You will enjoy the bright white look of silver at a fraction of the cost.