Gemstones Value
- Ivo Valente

- Jul 21
- 4 min read

Gemstones have no universally accepted grading system. Diamonds are graded using a system developed by the Gemological Institute of America (GIA) in the early 1950s. Historically, all gemstones were graded using the naked eye. The GIA system included a major innovation: the introduction of 10x magnification as the standard for grading clarity. Other gemstones are still graded using the naked eye (assuming 20/20 vision). A mnemonic device, the "four Cs" (color, cut, clarity, and carats), has been introduced to help describe the factors used to grade a diamond. With modification, these categories can be useful in understanding the grading of all gemstones. The four criteria carry different weights depending upon whether they are applied to colored gemstones or to colorless diamonds. In diamonds, the cut is the primary determinant of value, followed by clarity and color. An ideally cut diamond will sparkle, to break down light into its constituent rainbow colors (dispersion), chop it up into bright little pieces (scintillation), and deliver it to the eye (brilliance). In its rough crystalline form, a diamond will do none of these things; it requires proper fashioning and this is called "cut". In gemstones that have color, including colored diamonds, the purity, and beauty of that color is the primary determinant of quality. Physical characteristics that make a colored stone valuable are color, clarity to a lesser extent (emeralds will always have a number of inclusions), cut, unusual optical phenomena within the stone such as color zoning (the uneven distribution of coloring within a gem) and asteria (star effects). Apart from the more generic and commonly used gemstones such as from diamonds, rubies, sapphires, and emeralds, pearls and opal have also been defined as precious in the jewelry trade. Up to the discoveries of bulk amethyst in Brazil in the 19th century, amethyst was considered a "precious stone" as well, going back to ancient Greece. Even in the last century certain stones such as aquamarine, peridot and cat's eye (cymophane) have been popular and hence been regarded as precious, thus reinforcing the notion that a mineral's rarity may have been implicated in its classification as a precious stone and thus contribute to its value. Today the gemstone trade no longer makes such a distinction. Many gemstones are used in even the most expensive jewellery, depending on the brand-name of the designer, fashion trends, market supply, treatments, etc. Nevertheless, diamonds, rubies, sapphires, and emeralds still have a reputation that exceeds those of other gemstones. Gemstone pricing and value are governed by factors and characteristics in the quality of the stone. These characteristics include clarity, rarity, freedom from defects, the beauty of the stone, as well as the demand for such stones. There are different pricing influencers for both colored gemstones, and for diamonds. The pricing on colored stones is determined by market supply-and-demand, but diamonds are more intricate.

Cutting and polishing
A few gemstones are used as gems in the crystal or other forms in which they are found. Most, however, are cut and polished for usage as jewelry.
The two main classifications are as follows:
Stones cut as smooth, dome-shaped stones called cabochons or simply cab. These have been a popular shape since ancient time and are more durable than faceted gems.
Stones which are cut with a faceting machine by polishing small flat windows called facets at regular intervals at exact angles. Stones which are opaque or semi-opaque such as opal, turquoise, variscite, etc. are commonly cut as cabochons. These gems are designed to show the stone's color, luster and other surface properties as opposed to internal reflection properties like brilliance.
Grinding wheels and polishing agents are used to grind, shape, and polish the smooth dome shape of the stones.
Gems that are transparent are normally faceted, a method that shows the optical properties of the stone's interior to its best advantage by maximizing reflected light which is perceived by the viewer as sparkle. There are many commonly used shapes for faceted stones. The facets must be cut at the proper angles, which varies depending on the optical properties of the gem. If the angles are too steep or too shallow, the light will pass through and not be reflected back toward the viewer.
The faceting machine is used to hold the stone onto a flat lap for cutting and polishing the flat facets. Rarely, some cutters use special curved laps to cut and polish curved facets.

Global Gemstones Market Growth:
The global gemstones market is projected to reach $47.48 billion by 2031, with a compound annual growth rate of 4.90% between 2024 and 2031.
Forecast
Investment into colored gemstones of high value has become a true bonanza for those who believed in gemstones as hard assets. The prices of gemstones can be either based on the liquidation value, the money you can get if you are forced to sell quickly at the bottom price, or per insurance value, the money you have to pay to replace a stone at the current asking price in the market. And while pricing can be challenging due to different market forces, insurance value usually is more than double the liquidation. My prediction is that the insurance value of today will become the liquidation value of tomorrow. In other words, what you ensure investment grade ruby, sapphire or emerald today, can be realized by a quick sale tomorrow. And if current trends persist, this will happen sooner rather than later.


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