The color of glass depends on the mineral or metallic oxides added to the glass batch. These metallic oxides include tin, silver, copper, vanadium, chromium, manganese, cobalt and iron.

Beautiful green glass made into a funky green bottle.

Soda-lime glass has an intrinsic greenish color not visible if the glass is thin. A real green, like in wine bottles, is created by adding chromium oxide. Green beer bottles are created from glass with iron oxide added.

Sample of one green color used for beer bottles.

Manganese is added to soda-lime glass to counter the intrinsic green color, and make the glass a purple if more is added.

A medium purple and medium amber glass.

Cobalt is added to glass to make it blue, suitably enough. This color is the favorite of the blue bottle collectibles owners.

A sample of a cobalt blue bottle.

Copper oxide make glass a turquoise color. Nickel creates colored glass from blue to violet to black.

Dark red is a very attractive color of glass.

Gold is used to create ruby glass. If the glass does not have as much gold added, it is called cranberry glass.

Cranberry glass vase.

Selenium and copper also produce red colors.

Red glass comes in many shades, of which this is one.

Silver produces colors from yellow to orange. The only reason you need to care about how the color is created is in specific cases. If you are collecting ruby glass items, you need to know that it involves gold, and therefore will be more expensive. If you find red glass items that are less expensive, you must suspect that it is colored using some other method than gold, and decide if you really want these other kinds of glass. With other colors of glass, the colorant is less important.

Blue bottle with clear glass stopper.

For more information, go to Wikipedia and search for “glass coloring and color marking.”

The images on this post are from Stock Xchnge, except for the two with the blue velor background, which are by the author.

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