Are Moonstones Expensive?

The gentle, billowing light that shines from within moonstones is one of the most recognizable features that any gemstone exhibits. Fortunately, the IGS Price Guide shows that moonstones are often modestly priced, making even high quality gems attainable for many. Small, commercial quality stones may be priced $20 per carat or lower. Good-quality gems are often valued at about $125 per carat. 

When valuing moonstones, industry professionals are most concerned with the quality of the adularescence, bodycolor, clarity, and size. There are other factors that must be considered as well. Let's examine those characteristics so that you know what to look for when shopping for moonstones. 

The Most Important Value Characteristic for Moonstone Is the Quality of Its' Adularescence

Hands down, the most sought-after characteristic of moonstone is its adularescence. While you are probably familiar with the appearance of adularescence, you may not know the word itself. The term "adularescence" comes from an antiquated name for moonstone "adularia". Adularia references an ancient source of high-quality moonstone in the city of St. Adular located in Switzerland. 

The word "adularescence" now describes the phenomenal characteristic of moonstone where a floating light illuminates the gem from the inside and moves about as you tilt the gem. This unique optical feature is created by the organization of the moonstone mineral itself. Moonstones are made up of two varieties of feldspar - orthoclase and albite. When moonstones are forming, both of these minerals are in a fluid state and intermingled with each other. As the gems cool down, the orthoclase and albite separate and create multiple layers stacked on top of each other that are a mere 0.5 microns thick. Light gets caught between these layers, causing it to diffuse. This makes it seem like the gems are lit from within from a mobile source. 

The best moonstones have a bright and clear blue adularescence. Some refer to this as a "blue sheen". Gems may also show a white or silver-colored adularescence.

Some rare moonstones have an internal structure that creates a cat's eye effect called "chatoyancy" or a four-rayed star effect referred to as "asterism". Based on their scarcity alone, such gems are very valuable.

Bodycolor Matters

It is important to understand that the color of the adularescence is separate from the bodycolor of the gem itself. You may see gems that are colorless, white, orange, brown, yellow, peach, green, gray, and a dark gray that is almost black. Of all of these options, the most valuable bodycolor of moonstone is colorless while brown, yellow, and pale green hues are considered marks against the gem and will lower the per-carat value.

Clarity is An Important Consideration

In the world of gemstones, clarity is a massive topic with many facets. When it comes to moonstones, there are two different types of clarity that most frequently come into play: fractures and transparency.

Because people are drawn to moonstones for their hypnotic, flawless adularescence, so any noticeable clarity features will markedly lower the value of a stone. Unfortunately, moonstones are relatively soft with a Mohs score of 6 - 6.5, and they have two cleavage directions. This means that fracturing can happen. Aggressive mining techniques that utilize explosives may cause breaks in the gem before it is even pulled out of the ground. Fractures jar those layers of orthoclase and albite out of alignment and create a visible line within the stone that interrupts the otherwise smooth adularescence. 

Transparency is the other aspect of clarity that is important in terms of valuing moonstones. There are multiple levels of transparency. For a gem to be truly transparent, you must be able to see into the gem with no cloudiness or obstructions. As transparency decreases, you move from semi-transparent to translucent. Gems that you cannot see into at all are called "opaque". The transparency of moonstones is wide, ranging from semitransparent to opaque. Gems with better transparency are valued higher. 

When one considers adularescence, bodycolor, and clarity together, the most valuable combination of features is a blue sheen shining on a colorless background that has a semitransparent clarity. While moonstones are not a notably rare gem, this particular constellation of traits is highly unusual and especially large crystals may earn per carat values of almost $400.

Cutting Style Affects How You See A Moonstone's Adularescence

We know that the most important value characteristic for moonstones is their intrinsic adularescence. But we also know that the sheen is caused by the diffusion of light in between layers of orthoclase and albite. As such, the direction that you look at the gem is very important. If cutters orient the top of the gem at an incorrect angle, the sheen will not be centered. You may not be able to see it at all. 

Most moonstone is cut into a cabochon shape with a flat bottom and domed surface. This is because that dome is the best way to highlight adularescence. Sometimes, designs will be carved onto the top of the cabochon. You are likely to see many gems cut with lunar-themed motifs like the man-in-the-moon. Also, beads that are threaded onto a strand are not uncommon. You will also encounter some faceted moonstones. Faceting does not highlight the adularescence to its best, but it does a good job of hiding clarity features which would be obvious if the gem was shaped into a cabochon. 

Size Of the Moonstone Crystal Impacts Value

A trend that holds true for most gemstones is that big stones are rarer than smaller gems. Thus, value increases alongside carat weight assuming all other factors stay the same. Moonstones are no exception to this rule. Fortunately, large moonstone crystals are not uncommon. This is why the per-carat value range listed above remains relatively narrow and there is not an astronomical jump in price point. However, in recent years, the discovery of large crystals of fine quality has decreased. This is something to watch.

Origin

The value of some gemstone species is directly connected to where they were mined. This happens for two primary reasons: reputation of the source and identifiable characteristics often seen in the gems. 

When mine gets a reputation, it may or may not be linked to quality. Often, these reputations grow around sources that are old and proven. There may be nothing special about the gems from a famous source, but the singular fact that they came from there may affect how much people are willing to pay to acquire them. 

The origin of individual moonstone gems may not have been recorded because it is not something that contributes significantly to the overall valuation. This is largely due to the face that many moonstones have a similar appearance. You may not be able to tell if a gem is from Asia or North America. Yet, some deposits are known for particular features. Moonstones are found on several continents, and, while there is certainly overlap in the appearance of gems, some deposits distinguish themselves by having more or less of a particular trait. A sizable moonstone with desirable features from a known origin that is of note may fetch slightly higher prices, but, since the value of gems is already relatively low, the difference usually isn't much.

Sri Lanka - There are not many moonstone mines in Sri Lanka, so inventory is hard to come by, but the gems that are mined are known for being of the highest quality. Many gems shine with a white adularescence. 

India - Depending on where you look, India has either commercial quality gems or fine stones. The low-middle quality gems have a wide range of appearances. You will see transparencies spanning from semitransparent to opaque, body colors that are colorless to white, and adularescence that is blue, silver, or white. Southern India is associated with fine moonstones. In 1997, moonstones were discovered that boasted a strong green bodycolor some called "parrot green". 

Myanmar - The appearance of moonstone from Myanmar overlaps considerably with the commercial-grade gems from India. 

A Final Note on Moonstone Value

While the popularity of moonstone has (if you will pardon the phrase) waxed and waned over the years, their magical ability to capture light is undoubtedly among the most special traits exhibited by any gemstone. Luckily, this June birthstone is also quite affordable and available in many different sizes and shapes. Whether you are drawn to gentle, colorless cabochons with the classic blue sheen and semitransparent clarity or prefer faceted gems with more color or a cloudier clarity, there are options to suit any jewelry style.