July 2014 Newsletter: The Importance of Fine Cutting

The conventional wisdom in the colored gemstone business is that color is paramount, with clarity a close second. Carat weight comes third, since it has such a large effect on value. Cut, while important, tends to rank last among the "Four C's."

Like much conventional wisdom, this assessment is not exactly wrong, but tends to miss the point. A fine cut is actually a high priority in colored gems, not least because it impacts color, and impacts other optical properties related to color, such as brilliance, luster and scintillation. In short, it is not that color always take precedence over cut, but rather that it's hard to have great color and brilliance without good cutting.

The most obvious example is windowing. A gem that is cut too shallow will show an area of diminished color in the center of the stone. If the pavilion facets are cut at an angle less than the critical angle, light will pass through the gem rather being reflected back to the eye as brilliance. The result is a dead area in the center of the gem.

Fire Opal, Mexico
Fire Opal from Mexico

A fine cut is distinguished by excellent symmetry and precise facet junctions. A precision-cut gem will often display a lovely geometric facet pattern as the pavilion facets reflect through the table. An important component of fine cutting is an excellent polish that maximizes the luster and sparkle of the stone. You can see a good example in the video of the radiant-cut morganite above.

The cutting of colored stones can be a complex matter and it is not always easy to evaluate fine cutting, especially in the case of precious materials like ruby and sapphire. It is quite a different situation compared with diamonds, where an "ideal cut" can be precisely defined. Every piece of rough colored stone presents its own challenges on how to get the best from the material. The goal is to produce the most beautiful result, while preserving as much of the precious material as possible.

We have always taken great pride in our cutting. We cut many of our gems ourselves from the rough material, and we recut many of the finished stones we buy. We don't offer a gem for sale until we are sure it is AJS Gem Quality. Fine cutting is an important component of our quality standards, and we believe that educated consumers increasingly value fine cutting in the gems they buy.


Notable Gems from the AJS Collection

This month we feature some fine new acquisitions to our collection.

Click on a photo to see the details for the item.

4.46 ct Mint Garnet, Kenya

4.46 ct Mint Garnet from Kenya

A lovely mint garnet in a pastel blue-green. The superb clarity and well-executed portuguese cut make this a dazzling gem with impressive fire. Guaranteed natural and untreated.

See the video

10.37 Morganite, Brazil

10.37 ct Morganite from Brazil

An exquisite peach morganite with wonderful fire. This fine material has been precision-cut in a modified radiant cut and polished to perfection. This gem is sure to please the most discriminating collector and will look stunning when set in your jewelry design. Guaranteed natural and untreated. 

See the video

5.37 ct Unheated Ceylon Sapphire

5.37 ct Unheated Blue Sapphire from Sri Lanka

This is a very special gem -- gorgeous color, completely untreated, with outstanding clarity. Certified by GemResearch Swisslab (GRS) as natural and unheated, with origin noted as "Sri Lanka." Excellent vibrant color, beautiful material. This stunning gemstone is very clean and superbly cut, with great proportions and polished to a high brilliance.

See the video

5.74 ct Mexican Opal

5.74 ct Mexical Opal  [SOLD]

A superb orangey-red Mexican fire opal in a large size! This rare gem has an amazingly vivid color with remarkable transparency and perfect clarity. This rare gem has been precision cut with an excellent polish. Guaranteed natural and untreated.

21.37 ct Aquamarine, Brazil

21.37 ct Aquamarine from Brazil  [SOLD]

A superb large aquamarine with excellent color saturation and perfect clarity. Precision-cut with superb luster, this is a top grade gem that will delight the most discriminating connoisseur. Guaranteed natural and untreated.

5.31 ct Chrome Tourmaline, East Africa

5.31 ct Chrome Tourmaline from East Africa

A beautiful chrome tourmaline trillion in the classic deep emerald green color. Very clean with very good fire. This fine gem has been precision cut to maximize fire and brilliance. Guaranteed natural and untreated.


News from AJS and the Gems World

  • GemFields Sells $33.5 Million at First Ruby Auction 

    GemFields Plc held their first auction of ruby and corundum from their Montepuez ruby deposit in Mozambique. The auction was held June 12-17 in Singapore. Auction sales totalled $33.5 million and 92% of the lots were sold, with buyers attending from Thailand, the USA, India, Israel and Germany. Gemfields also owns the Kagem emerald mine in Zambia, and the company is listed on the AIM exchange in London.

  • Chow Tai Fook to buy Hearts on Fire for $150 million

    In another indication of the importance of China to the world gemstone trade, China's largest jewelry retailer and manufacturer, Chow Tai Fook, has agreed to purchase US-based diamond jewelry manufacturer Hearts on Fire for $150 million. Chow Tai Fook owns more than 2,000 jewelry points of sale in China and Hong Kong and had revenue of approximately $10 billion in the most recent fiscal year.



Ask the Gem Experts

Each month we answer questions from our customers. We welcome your questions and you can submit a question from our contact page.


When you describe a gem as "heated", does it mean it might have been heated with a foreign substance?  YW, USA

All gems that we list as "heated" have been treated with simple heat only. Any sapphires which have been heated with beryllium are described as "heated/lattice diffusion." Please note that we don't deal in any glass-filled rubies or sapphires, and advise against purchasing them, since the treatment is not stable.


I saw a beautiful pair of round demantoid garnets on your website, are they still available?  SL, Australia

We did have a rare matched pair of 2 carat demantoid garnets, with a combined weight of 3.99 cts. We're sorry, these have now been sold. We set them in 18k gold earrings for a customer and we have a photo you can see in our Jewelry Gallery.



All the best in gems,

Arnold, Rung & Ron