Common Colors
White, brown and green sea glass pieces are among the most common because more glass containers were made in these colors than in other colors. White beach glass was originally clear glass and likely came from bottles or jars. Green or brown sea glass is often from wine, beer, rootbeer or ginger ale bottles. Some shades of greens and browns are more rare, however. Lime green sea glass is hard to come by, as are some lighter brown shades, such as amber or golden brown.
Mid-Range Commonality
Other colors of sea glass are still common but not found as readily as the greens, browns and whites mentioned above. Aqua sea glass often came from old soda bottles. Light green or "seafoam" green glass also falls into this category, as do some of the lighter shades of brown, such as honey brown.
Rare Colors
If a glass color is rarely found in product containers, it's also an unusual sea glass color. Sky blue, pink, lavender, cobalt blue, yellow and bright lime green are rare sea glass colors. Older bottles that were once made in some of these colors -- such as cobalt blue Milk of Magnesia bottles or bright green lemon-lime soda bottles from the mid-20th century -- will eventually break down into smaller bits over time once they are in waterways, making it harder to find sizable pieces of these colors. Bear in mind that glass color rarity may vary depending on where you search; rare glass colors in the United States may be more common on older beaches in other countries, for instance.
Very Rare Colors
Unusual glass colors such as turquoise, bright purple, deep red, black and orange are hard to find in sizable pieces and are therefore more prized by collectors. Modern bottles and glass containers in these colors are not as common, which means there are fewer of them getting into the waterways. If you look closely and for a long time along beaches where sea glass is found, you may find tiny pieces of these treasured glass colors.