Chatham’s A – Z Glossary


The chameleon of gemstones, Chatham lab-grown alexandrite has a unique ability to transform from a bluish teal to a reddish purple. Grown from the finest Russian-mined seed crystal, it takes about 9 months to a year for Chatham Alexandrite to grow. Chatham began growing this color-changing Chrysoberyl in 1972. Due to its distinctive phenomenon, alexandrite represents willingness for change and adventure. This rare gem is an ideal gift for that special someone who is as unique as an alexandrite.

Blue Brilliance

This lab-grown diamond characteristic is caused when small traces of the element boron fuses with carbon during the diamond growth process. This can only occur using the High Pressure, High Temperature (HPHT) method of growth.  Diamonds that exhibit this distinct attribute remain colorless or near colorless with a slight bluish tint that brings the diamond to life. Also known as blue-white.

Carroll Chatham

In 1938 Carroll Chatham, an American chemist, revolutionized the jewelry industry when he became the first ever to grow gem quality emerald crystals in a laboratory.  About twenty years later, he began growing other mineral crystals such as ruby, alexandrite, and a variety of sapphires. This great achievement made it possible for the industry to offer rare gems in jewelry designs at a more affordable price. Today, the company that bears his name is the world’s leader in laboratory-grown gemstones and jewelry.


Diamond is the hardest mineral on earth and comprises of a single element, carbon. Admired for its undeniable beauty, diamonds have been worn by royals, starlets, and brides for centuries. Given as the traditional engagement stone, diamonds have been cut in variety of shapes including rounds, ovals, cushions, princess, and more. Diamonds form through intense heat and pressure underneath the earth’s surface. To find a mined diamond takes a lot of resources and time. Chatham grows diamonds in a laboratory mimicking the conditions deep underground. There are two methods of growth: Chemical Vapor Deposition and High Pressure, High Temperature. Both methods produce a range of quality grades.


This lush green variety of beryl is where the Chatham story begins.  While Carroll Chatham was away at college, he left his latest experiment running in his parent’s San Francisco garage. One evening, his father noticed and turned off the power supply to his experimentation. This unassuming act caused the emerald crystals to grow inside the crucible: the first ever to grow above ground with the assistance of man. It took Carroll quite some time to understand how this simple act caused the crystals to form. But when he did, he began a lifelong career in pursuit of offering the industry miracles of nature himself.


Chatham’s proprietary methods are kept a secret to this day. But the flux-method has been one of the processes publicly used to grow Chatham gemstones. The process starts when an earth-mined seed crystal is placed in a crucible. Inside the chamber, we mix the ingredients needed to feed the crystal growth with a solvent (flux). We seal the chamber and set the temperature at 1100 degrees Celsius! After a period of about 9 months to a year, we unlock the chamber and discover what has grown inside.  Gemological institutes train their gemologists to identify characteristics only found in flux-grown gemstones: flux fingerprints or flux-filled inclusions. In addition to cutting away about 80% of our rough, Chatham’s growth technology has evolved so much throughout the years that we are able to deliver internally flawless stones.


Gemstones are our specialty! Chatham is able to offer rare, beautiful gems that possess the same optical, chemical and physical properties as their mined counterparts. Chatham is conscious of our beautiful planet and neighbors. That is why we only promote sustainable and ethical growth. Our loose gemstones can be found in over 8,000 locations across the globe. We only partner up with independent retailers who possess strong ethical values and are heavily involved with their communities. Search here for an authorized retailer in your area. 


Known as the High Pressure High Temperature method of diamond growth, this process duplicates more closely what happens in nature. By combining 725,000 PSI of pressure with 1300 degrees Celsius, we are able to grow up to around 10 carats of diamonds. If you were to use this same method at a much lower pressure, the result would be graphite. It is necessary to own a large diamond press in order to use this method of growth. These diamond presses run for about $500K each! While most believe it is inexpensive to grow diamonds, the opposite is true. It is more costly to grow a diamond in a laboratory than it is to mine the earth. HPHT grown diamonds produce some of the highest color and clarity grades.

Ice Analogy

What Chatham does with gemstones in a laboratory, is what you do everyday at home with ice. You place the starter material, water, in an ice tray and you place it into a controlled environment, your freezer. By controlling the temperature and the time, ice crystals begin to form naturally. Even though it was made by man, it is frozen H2O nonetheless. And because you were able to control the environment, the ice in the freezer is cleaner without the impurities found in a lake. 


In 2007, Tom’s lifelong friend, Harry Stubbert, partnered up with Tom Chatham. Harry brought his combined years of experience with his long-term vision for Chatham and decided to completely reposition the brand to include a line of finished jewelry featuring its lab-grown gemstones. His idea was to introduce designer cuts exclusive to the brand that could not be replicated with earth-mined gemstones. Cuts like the onion or flame and elongated versions of the oval and pear shapes. Today, Chatham has collections in every jewelry category: bridal, color fashion, diamond fashion, initials, and statement pieces. Customers from around the world appreciate and admire the work we are doing. Chatham has partnered up with independent retailers across the country to offer you our finished line of jewelry. Search here for an authorized retailer in your area.

King of Gems

Ruby’s value is so well respected; it is the only corundum that was given its own unique name. This noble gem was the second stone that Carroll Chatham began growing after emerald. The year was 1958. Same as with emerald growth, it took some time to discover the science behind growing ruby. In 1965, Carroll’s youngest son Tom joined the team and was assigned the task of learning ruby flux growth. Today, ruby is one of our best selling stones admired for it rich color and highly regard reputation. 

Laboratory Grown

In 2018, the FTC recognizes the term laboratory-grown diamond to describe a diamond that grew in a lab. They went one step further and removed the term synthetic from its recommended list of terms to describe laboratory-grown diamonds. While it is not prohibited, it must be used in way that does not imply they are not actual diamonds. Chatham uses the term laboratory-grown to describe all of our gemstones, including diamonds.  It is the simplest way to differentiate between a laboratory-grown gemstone versus an earth-mined gemstone. The difference is the environment in which they grow, not what it is.

Moh’s Scale

Similar to Carroll Chatham, Friedrich Mohs studied chemistry and had a passion for minerals. He came up with a scale that classified minerals based on their physical characteristic rather than chemical composition. The scale is a set of numbers 1 through 10 and he classified minerals based on whether they could be scratched by others. The hardest mineral, diamond, was assigned the value 10 and the softest mineral was assigned value 1. Although the numbers are in numerical order, it does not mean the difference in hardness is equal – it varies. Today we use this scale to determine the hardness of a gemstone. This is especially useful for stone setters and jewelry designers when determining if a gemstone is suitable for everyday wear. 


This is a term we used to describe the difference between a gemstone mined from underneath the ground to one grown in a laboratory. We have since updated the term to earth-mined. Chatham does not deny the beauty and mystique that earth-mined gemstones possess. We simply offer an alternative. Perhaps affordability is a motive. Maybe it is the color quality of our lab-grown stones that appears more attractive. It could be the sustainability factor that drives the customer.  It’s possible they are chemistry buffs and appreciate the science behind it. Or, they just simply like the design! The important thing is that we support the jewelry business and we are grateful to be a part of an ever-growing industry. An industry that offers all options where the consumer can make their own educated choice!


Chatham offers three varieties of opal: white, black and crystal. We began growing using the Gilson method in the early 2000’s, when we bought the rights to the formula. This ensured quality and consistency. Opal is the only mineral we grow through sedimentation. The unique play-of-color that brands this gemstone so magical is caused by internal diffraction – small silica spheres in grid-like structures break up light into spectral colors. The result is an array of vibrant colors dancing on the entire surface of the opal. White and black opals are typically cut as cabochon while crystal opal can be cut into a wider range of shapes. We recommend a faceted pavilion with a buff top – simply stunning!


Named after the Sinhalese word for lotus blossom, Padparadscha is a gorgeous combination of peach and pink. This exotic gem is quite rare in nature. True padparadscha sapphire is mined from Sri Lanka. In order to grow this gem with the sought-after color that makes it truly special, Chatham places a crystal seed from Sri Lankan mined padparadscha into a crucible. During a period of about 6 months, we allow the crystals to grow naturally. The result is the ethereal orange-pink color seen in our line of jewelry. Padparadscha is a great gift idea for someone who is creative, self-expressive and confident. It also represents peace and enlightenment just like the sacred lotus.


For over 80 years, Chatham has evolved and refined the technology behind our processes. We pride ourselves in delivering the highest quality gemstones and jewelry with our uncompromising standards. No matter which shape we cut, we follow strict guidelines for proportions, faceting and polish that ensure that all our gemstones have maximum brilliance, high clarity, and vivid color. To meet these criteria, 80% of the rough crystal is lost. Saving extra weight is never a consideration. During gemstone selection for our jewelry collection, we handpick one crystal in 200 that meets the strict standards of color and clarity. If that isn’t enough, we guarantee our quality for life through our Lifetime Warranty.


Worn by both queens and warriors alike, rubies hail as the King of Gems. The deep, intense color in ruby is caused by its chromium rich content. It is no surprise that the flame cut that we have designed exclusively for our fine jewelry collection is the most popular ruby shape. The ruby flame conjures passion and intensity, an ideal anniversary gift! Myanmar, formerly known as Burma, grows the finest quality rubies on the planet. Because of recent geopolitical negatives surrounding the country, Chatham lab-grown rubies are the perfect alternative. Since we cut away about 80% of the rough to deliver the very best in color and clarity, Chatham is a great substitute for earth-mined goods. And since we grow using a seed crystal from Burmese ruby, you now have the confidence of knowing that it is chemically, physically and optically identical to the most sought after mined-rubies.


Year after year, sapphire leads as the most desired Chatham lab-grown gemstone. Maybe it’s the cool, easy color on your eyes. Perhaps it’s the ease with which it goes with everything in your closet. Or it’s because the color blue continues to be the most popular color for both men and women to this day! Chatham lab-grown sapphires display a beautiful shade of blue reminiscent of Ceylon sapphires. That is because we use a Ceylon-mined seed crystal to grow from. Sapphires make great gifts: something blue on the wedding day, a family heirloom, a baby (boy) shower gift, a graduation gift, and a just-because gift! Sapphires represent loyalty and honesty. The beauty of this gemstone is its versatility. It looks stunning in any shape, can be dressed up or down and brings out the twinkle in any girls eye.

Tom Chatham

In 1965 Carroll’s youngest son, Tom Chatham, joins his father Carroll, in the original San Francisco research laboratory. His first job was figuring out ruby flux growth, something never accomplished by anyone yet in the world. At the same time, his interests in marketing began to form and he determined that a more effective business strategy was to sell faceted gemstones rather than providing industry buyers with rough. After many years and many countries, Tom built relationships with prominent cutters who remain Chatham’s master cutters to this day. In 1976, Tom was appointed President of Chatham Created Gems, Inc. In 1993, he achieved his father’s lifelong dream and grew Chatham’s first ever colorless diamond.

University of Maryland

Chatham is an active advocate for education and believes that inspiring forward-thinkers is the greatest investment above all. For nearly a decade, Chatham has donated loose gemstones and/or jewelry to the University of Maryland’s annual Gem Grab Bag Auction. This initiative provides scholarships to students who face financial hardship and are unable to complete their education. Through these contributions, Chatham helps raise funds to grant these scholarships. Nothing makes us prouder than knowing we have made a significant impact in the lives of these young minds. Over twenty Maryland Parent and Family Association Student Scholarship Awards have been granted.


Besides the HPHT method of diamond growth, Chatham also grows using the CVD method, Chemical Vapor Deposition. In this process, methane gas is subjected to high-energy plasma radiation. Methane is CH4: it has one carbon atom and four hydrogen atoms. We use microwave energy heat to break the atomic bonds in methane and to free the carbon to float down and attach to a diamond seed, growing a diamond crystal atom by atom. This process produces a wider range of quality in clarity and color.


One of the best promises we can extend our customers is our quality guarantee. Chatham offers a Lifetime Warranty on all of our lab-grown colored gemstones. Our promise is that you can wear your Chatham gemstone jewelry everyday without worry. If your Chatham lab-grown gemstone chips or breaks, please take it back to the jeweler where you purchased it. Make sure to bring your Certificate of Authenticity or Lifetime Warranty Card. Your retailer will send it back to us for an evaluation. We will either repair or replace the gemstone depending on the damage. Consideration will be taken to honor the original size and weight of the stone. Normal wear and tear is excluded.


Science, innovation, technology and creativity are the pillars that sustain Chatham. But our secret weapon, or X-factor, is the team of master cutters that hand cut each individual stone, bringing life to a rough crystal. Cutting and faceting gemstones take extraordinary amounts of skill. Our cutters are required to take a 6-month training program before they cut a single Chatham lab-grown gemstone. Cut and proportion are essential in enhancing the look of a gem.

Yellow Sapphire

The color yellow is universally the happiest color on the wheel. It inspires optimism and energy. Lucky for us, Chatham has three shades of this jovial color to offer: light, medium and dark. These colors are only offered as loose gemstones. Our only jewelry collection featuring yellow sapphire is the Initial Collection, which features the medium tone.


Color zoning is a term to identify uneven color distribution within a gemstone. This is especially prevalent with sapphires and as it turns out, Chatham lab-grown sapphires as well! During the growth process, sapphire follows the crystal structure in color zones. Often times, the result is a piece of rough displaying different shades. That is why we are able to offer more than one shade (loose only). Color uniformity is important to us and that is why we cut away about 80% of the rough.