Mercury, or silvered glass, is glass that has a silvery appearance. Mercury glass actually contains no mercury, although there were at one point, several manufacturers who attempted to line glass with mercury. This procedure was short lived due to both the toxic nature of mercury as well as its expense, but may account of the name of mercury glass.

Although glass collectors are not often interested in mercury glass, more and more antique hobbyists are becoming collectors of this particular form of glass. Although it is also called silvered glass, it contains neither silver nor mercury. Mercury glass is, instead, clear glass which is mold-blown into double-walled shapes. The glass is then coated on the inside with a liquid silver nitrate solution, through a hole in the bottom.

Mercury glass was first created in Germany in the early 1800s. It was used as a more inexpensive material for candlesticks, vases, goblets, and other objects. Silvered glass quickly gained popularity in France, England, Bohemia, and the United States. The New England Glass Company showed a large display of the glass at the New York Crystal Palace Exhibition in 1853; included in the display were goblets, vases, spittoons, sugar basins, tumblers, and more.

Although some critics dismissed mercury glass as being too showy and looking too mirror-like, most people found it very attractive. Soon, silvered glass began to be decorated with enamel, etching, paint, and engraving. In the twentieth century, the glass was used to make Christmas ornaments and other household decorations.

Silvered glass is fairly inexpensive, but is often flawed due to oxidation which makes the silvered surface flake off. Air is able to enter through the hole in the bottom which is necessary for the silver nitrate solution, and reacts with the surface. To slow or avoid this oxidation process, a cork or wax plug can be placed in the hole to seal it and arrest the process.

Mercury glass ranges widely in price. Pieces can be found for no more than a few US Dollars (USD) at flea markets, or for over $1,000 USD. Most pieces that are in reasonable condition are continuing to increase in price, however, as the glass attracts a following among collectors.