Agate Buying Guide
Decorative, patterned forms of agate are excellent natural gems. This variety of chalcedony takes on a number of forms, most commonly banded with color, but sometimes with lovely inclusions that look like moss, trees, or even entire landscapes. Agate, the alternative birthstone for Geminis, is affordable even in large sizes. It can be used for jewelry or to make decorative items. Before your next agate buying trip, learn more about the rare and beautiful forms of this gem material.
Agate Buying and the Four C’s
Agates form in a wide variety of colors due to trace metals in the mineral’s chemical makeup. Vivid natural colors in agate will have a higher value than colors that are less intense or artificially dyed. Blue and green hues are the least common. They will command somewhat higher prices than red and yellow colors.
Moss, dendritic, and plume agates are the exception. Here, the inclusions create beautiful natural patterns, the hallmark features of these stones.
Agate cabochons or slices should attractively showcase the stone’s patterns. A proper cut will enhance the banding or inclusions to create a beautiful and appealing piece.
For carved or sculpted pieces, creative use of the natural patterns is most important. Accordingly, the artistic use of agate will add a premium to this gem’s cost. (Most of the expense is due to artistry and skill rather than the stone itself).
Found in all sizes, agate prices aren’t dependent on carat weight. In fact, agate slices the size of small tabletops are commercially available.
Because of the wide array of natural patterns, there are many different varieties of agate. Some of the more popular varieties for jewelry use are described here.
Most agates have bands or concentric circles of color. Those with several different vibrant colors can be stunning, but these often arise from artificial dyes.
With iridescence due to limonite inclusions, fire agates earn their name. Mined in Mexico and the southwestern United States, this gem often forms in a botryoidal habit, resembling grapes. One of the rarer forms of agate, this material is more expensive than other varieties, though still quite affordable.
Moss, Dendritic, and Plume Agates
Some agates contain attractive patterns of inclusions. Moss agates are one of the most sought-after varieties, with green inclusions that resemble moss. Similarly, dendritic agates have tree-like inclusions. Inclusions that resemble plumes or feathers give plume agates their name.
With delicate swirled bands, the patterns of lace agate are mesmerizing. When properly cut, this variety gains an exquisite beauty. Red layers are considered rare in lace agate.
Certain agates can showcase patterns that resemble scenes. For example, you might see snowy mountaintops, trees, and shorelines in these rare stones. Arguably, these make the loveliest, statement piece agates.
Petrified wood made of agate can be bright and colorful. In some cases, the original tree rings are visible with little magnification.
Silicified shells are another form of agate. “Turritella agate” is comprised of gastropod shells, commonly, but not necessarily, of the genus Turritella.
Dyes often embellish the color of an agate. Although dyed specimens are less valuable than their natural counterparts, the dyes are generally stable and can create a desirable color scheme for decorative items.