Sunday, February 26, 2012

Sea Glass Color Rarity Chart - How rare is your sea glass and why?

You can find sea glass in a range of colors, but some colors are more difficult to find than others. To understand why certain colors are more rare than others, let's first look at how glass is made. The additives that give the glass color are often expensive or difficult to obtain.

Most glass is made of 3 materials:
  • Silica (sand)
  • Soda (sodium carbonate)
  • Lime (calcium oxide)
90% of manufactured glass is made of silica, soda and lime, and is termed Soda-Lime Glass.


How do they make colored glass?

Metals and metal oxides are added to create a specific color in the glass.
The chart below shows what metals are used to make colored glass, as well as the sea glass rarity. Note that glass made using gold or silver was produced less often than other colors, resulting in a more rare piece of sea glass. Where does your sea glass fit on the chart?









Glass Color Metal or Metal oxide Sea Glass Occurrence Rarity

Orange Selenium and Cadmium Sulfide 1 in 10,000 Extremely Rare


Silver




Iron Oxide



Dark Purple Manganese Dioxide 1 in 10,000


Purple Nickle



Red (ruby or cranberry) Gold 1 in 5,000


Orange-red Iron Oxide



Dark Red (opaque) Copper




Silver




Selenium and Cadmium Sulfide



Turquoise Copper Oxide 1 in 5,000



Copper and tin




Cobalt with copper or iron



Yellow Uranium dioxide (glows under UV light) 1 in 5,000



Silver, Chromium, Zinc, Antimony, Iron, Minium, Nickle, or Cadmium – with Sulfur



Pink Selenium 1 in 3,000 Rare


Arsenic




Manganese



“Black Glass” (dark green or dark amber) Iron 1 in 2,500



Cobalt and Copper




Cobalt and Manganese



Teal Cobalt and Iron 1 in 2,500



Chromium




Aluminum Oxide and Cobalt



Gray Manganese 1 in 2,000



Nickle



Ice Blue Copper or Copper Oxide 1 in 2,000


Aquamarine Copper 1 in 1,000


Lime Iron 1 in 1,000



Uranium (glows under UV)




Chromium or Cadmium



Lavender/Amethyst Manganese (glows orange under UV) 1 in 1,000



Selenium



Citron (yellow-green) Oxidized Chromium and Potassium 1 in 500


Opaque white (milk glass) Tin Oxide or Zinc 1 in 500


Cornflower Blue Cobalt Oxide and Iron 1 in 500


Cobalt Blue Cobalt Oxide and Iron 1 in 300


Honey Amber Cerium and Iron 1 in 200 Uncommon


Manganese and Iron



Soft Green Iron 1 in 200


Seafoam Green (light green) Iron 1 in 100


Seafoam Blue (light blue) Iron and Copper 1 in 100


Forest Green Iron and Chromium 1 in 50


Kelly Green Copper and Iron 3 in 10 Common


Chromium and Arsenic or Tin



Root Beer Brown Iron and Sulfur or Carbon 3 in 10


White (clear) Manganese or Selenium 4 in 10



Cerium Oxide








If you notice in the chart, certain types of sea glass made with Manganese or Uranium will glow under a black light or UV light!

Brown and Kelly Green glass were typically used for beer and soda bottles, thus explaining how common those colors are in sea glass. A darker green, like Forest Green was used for wine bottles and still is. White (clear) was commonly used in soda bottles, food jars, juice bottles, and tableware. Flat pieces of white sea glass could be from tableware or windows.

The more rare colors of sea glass are most likely from decorative glass, like vases, art pieces, or tableware and explains why you do not find them as often.

Note that the rarity of sea glass can vary from location to location.

Visit my Etsy shop to see how I've reinvented my sea glass into jewelry!
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Sources:
http://en.wikipedia.org/wiki/Glass_coloring_and_color_marking

Pure sea glass: discovering nature's vanishing gems (2004) by Richard LaMotte, Sally LaMotte Crane, Celia Pearson.