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


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


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



“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


Aluminum Oxide and Cobalt

Gray Manganese 1 in 2,000


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


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!


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

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