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Lab Grown
Buying Guide

Gemstones are a miracle of nature:
a miracle that has now
been recreated
by man.

Chatham is proud to be the pioneer of lab-grown gemstones.

These gemstones have the same physical, chemical, and optical properties as mined gems do. We don’t “make” gems. We control the environment so that crystals can grow naturally: recreating the conditions in which gems grow in the earth.

The process of growing gem crystals in a laboratory rather than mining them is a bit like making ice in your freezer instead of finding it in a lake. You place the starter material, water, in a container, and put the container into a controlled environment: your freezer. Create the right conditions of temperature and time and ice crystals will form. The freezer ice will usually be cleaner and more perfect than lake ice because you can carefully control the environment. But it’s still ice, just like the ice that forms in nature. In a way, what we do is a sophisticated high-tech version of freezing water to form ice.

One of the benefits of lab-grown gemstones is that they have less of an impact on the environment than mined gems.

Lab Grown Gems



Are Chatham Created Gemstones real? Or are they artificial?

Our lab-grown gemstones and diamonds are cultured just like you would culture a pearl. Natural ingredients are placed in an environment created to duplicate nature. Once the required combination of chemical and environmental factors is created, gemstone crystals grow over the course of about a year (the exact length of time depends on the variety). As a result, the crystals we grow have physical, chemical, and optical properties that are identical to those found in nature.

Can I tell the difference between created gemstones
and mined gemstones?

Unless you’re a certified gemologist with a powerful microscope, you won’t be able to tell the difference between Chatham-created and mined gemstones. Every gemological laboratory in the world has reference samples of Chatham Created Gemstones to aid in the separation. Chatham is at the forefront of full disclosure, contributing samples and updates whenever something new is released.

Why do Chatham gemstones and diamonds look better
than their mined counterparts?

Under laboratory conditions, computers control temperatures, while foreign materials found in the earth are eliminated from our starting chemicals. This makes our crystal growth more predictable and consistent. We strive for the best qualities and colors found in nature. Lower qualities are not released for sale.

Are there cost savings with lab-grown gemstones?

The price difference between Chatham and mined gemstones of similar quality can be dramatic, especially in fine qualities. For fancy colored diamonds, it can be as much as $100,000 per carat. In other varieties, like colorless diamonds, the difference varies from 30% - 80% depending on the size, shape and quality of the diamond. The price difference increases substantially as the weight and quality of the diamond rises.

Does Chatham offer a warranty?

Yes. Trust, integrity, and value are at the heart of Chatham and our products. For your peace of mind, we provide a Lifetime Warranty for all Chatham-created gemstones and a Certificate of Authenticity for Chatham jewelry pieces. Chatham will gladly repair or replace your stone at no charge if it should chip or break under ordinary circumstances, or if any defect in the workmanship or materials become apparent. If you question whether your damaged jewelry is covered under our warranty, please return it along with the sales receipt, to the store where the item was purchased. Then, your Chatham retailer will expedite the item to Chatham for immediate servicing and, if a replacement gem is needed, consideration will be taken to honor the original size and weight.


Are these stones enhanced or color treated?

No. All of Chatham’s gemstones are grown in a lab under a controlled environment producing the most vividly saturated color possible. The chemical structure and coloring agents are the same as its mined counterparts.

Are lab-grown gemstones as durable as mined gemstones?

Yes. In fact , you will find that Chatham stones are more durable because they have fewer inclusions than most of their mined counterparts.

This is because we cut away 80% of our rough to deliver near “flawless” pieces. The hardness of Chatham’s stones are exactly the same as their mined counterparts. In addition, Chatham offers a Lifetime Warranty, which is something you will not find for any mined gemstone.

Are lab-grown gemstones “green”?

No products have zero environmental impact. But it’s true that the production of our lab-grown gemstones does not require moving large amounts of earth like mining. There’s also no chance of drinking water pollution. Crystal growers do use energy and chemicals derived from the earth but the carbon footprint of crystal growth is a small fraction of natural gemstone mining.


vsLab Grown


Would a rose by any other name smell as sweet? People have used lots of words to describe laboratory grown gemstones, some a bit sweeter than others.

What we’re all trying to do is to find language that communicates clearly without confusing consumers. Unfortunately, there are so many terms for lab grown gems out there (and some bad apples who are actually trying to confuse people) that there isn’t always as much communication as there should be.

We prefer to call our gems “lab-grown” because we feel it most clearly describes what they are. We are crystal growers.

When Carroll Chatham grew his first emerald crystals in the 1930s, the jewelry industry was worried that the value of natural gems would collapse. They were also worried they wouldn’t be able to tell lab-grown emeralds from mined emeralds.

In 1959, the Federal Trade Commission stepped in to make strict rules about what companies like ours could call their products. The commission ordered Carroll Chatham to release all the details of his process in order to decide whether his gems could be called “cultured.” Because he refused to divulge the secret of how his gems were grown, Carroll agreed to stop calling them “cultured” and to call them “Chatham-created.”


Those worries from the natural gem industry are still there. So is a lot of prejudice against our products from people who don’t understand them. (And, frankly, not all jewelers can tell the difference between mined and lab-grown even today.) Scientists (and natural gem enthusiasts) often use the term “synthetic” to describe lab-grown gems. But when we talk to consumers, we find that most people think it means “imitation” or “artificial,” so we don’t use it. If you heard “synthetic diamond” would you think of a high-tech laboratory-grown diamond that costs thousands of dollars a carat or would you think of a cheap imitation?

Other terms that are often used to describe lab-grown gems are “lab created gemstones,” “synthetic gemstones,” “created gemstones,” “lab gemstones,” “man-made gemstones,” and “cultured gemstones.” These are good ways to describe lab-grown gems too as long as they are used correctly.

To make this debate about nomenclature even more confusing, there are some gem materials that are man-made and also imitations. Cubic zirconia is man-made but it’s an imitation diamond, not a synthetic or lab-grown diamond (because it’s not actually diamond.) Unfortunately, plenty of unscrupulous people use “lab,” “man-made,” or “created” to refer to imitations that are not the actual minerals described. That’s not just bad etiquette. That’s deceptive and clearly against FTC rules.

We also think consumers should know the difference between inexpensive flame fusion or pulled created gemstones and the more expensive lab-grown gems. Not all gem varieties can be made inexpensively by flame fusion or pulling: sapphire, ruby, and spinel are the main ones. That’s how sapphire watch crystals are made.

In these inexpensive processes, powdered chemical ingredients are melted into a large block in an hour, not grown as crystals over a year. The crystal structure of flame fusion or pulled synthetics is disoriented, like glass, due to the way it’s made. It doesn’t have natural crystal faces. From a crystallography perspective, flame fusion isn’t the same as mined ruby or sapphire.


Chatham flux-grown
ruby rough

The crystal structure of flux-grown ruby or sapphire is the same as mined ruby and sapphire. Its internal structure is identical. That’s why it’s worth devoting a year to letting it grow. Because the structure is identical, you get the same brilliance and reflection from the crystal structure and that is why people fall in love with gems in the first place.

In the end, that’s what this is all about: understanding what the differences are between different kinds of gems so you can make an informed smart choice: mined, lab-grown, man-made, or imitation. It’s up to you!

our process

Our Process

Growing Colored Gemstone Crystals
Every Chatham lab-grown gemstone gets its start with a naturally- mined crystal slice placed inside a crucible chamber. We fill the chamber with a liquid containing the ingredients needed to feed crystal growth. This “liquid” is only possible at 1100 degrees Celsius! Looking into the chamber is like looking into a volcano.

Then we seal the chamber and wait. A long time. In fact, for most of the gem varieties we grow we wait from six months to a year!

The chamber’s temperature and chemistry are carefully controlled to duplicate the conditions inside the part of the earth where that gem variety forms. Slowly the crystal begins to grow on the seed in its natural crystal shape. Once this process ends, you have a crystal rough identical to one found in nature. Chatham’s gemstones contain the same physical, chemical, and optical properties as their naturally-mined counterparts.

It is still a “WOW” event every time we open up a crucible that has been untouched for 10 months. Sometimes it’s a big disappointment too. We are always experimenting by changing little things to see if we can improve the quality of our crystals. Experimentation is the key to continuing to innovate.

Every time there is an earthquake or power is lost for any sustained amount of time, crystal growth is interrupted and all the batches we are growing are lost. Any loss of power longer than 10 minutes will be visible in our crystals. This is why, although we love San Francisco, Chatham made a major decision in 1989 to diversify and grow crystals in different cities around the world. Today in addition to San Francisco, our gems are grown in France, Greece, Japan, Russia, and China.

our process

our process

Growing Diamond Crystals
Unlike the other gems we grow, diamond is a single element: carbon. In some ways that makes things easier. The fewer variables there are, the easier the growth process. We grow diamond using two processes: HPHT (high pressure, high temperature) and CVD, or chemical vapor deposition. In the HPHT process, we grow crystals as large as 10 carats using 50 kilobars or 725,000 PSI of pressure at 1300 degrees Celsius. If you tried to grow diamond without high pressure, you’d just get graphite. The equipment required is massive: our largest diamond press is three stories tall! It produces about 100 carats at a time in about a week to ten days. Like mined diamond, there is a lot of variety in color and clarity. Not everything we grow can be cut into a beautiful gem.

We grow fancy colored diamond crystals because of the demand for these gems. They are so rare that vivid pinks from a mine can be a million dollars or more a carat! Even though it’s very expensive to grow these gems, it’s much more affordable than natural crystals!

To grow colorless diamond crystals using the CVD 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 the methane and free the carbon to float downand attach to a diamond seed, growing a diamond crystal atom by atom. Diamonds that grow this way can be remarkably pure.

When everything goes well, it takes about 10-12 days to produce 140 carats of crystals that are 8-9 carats each. But there are still huge technical challenges that everyone who uses this growth method faces. That’s why production of diamonds using CVD is still quite limited.

Growing diamonds is challenging and expensive. That’s why they cost only about 20% less than mined diamonds. That’s also why many companies that specialized in lab-grown diamonds that got a lot of press eventually went out of business.

our process

our process

From Crystal to Gem
After studying each crystal’s shape and internal inclusions, we decide which shape to cut. We cut traditional shapes and some innovative new ones like the onion cut and the flame cut that we’ve designed exclusively for our fine jewelry collection.

No matter which shape we cut, we have strict standards for proportions, faceting and polish that ensure that all our gemstones have maximum brilliance, high clarity, and vivid color. To meet these standards, 80% of the rough crystal is lost. Saving extra weight is never a consideration.

For our jewelry collection, we select one crystal in 200 that meets the strict standards for color and clarity.