Unveiling the Brilliance: Lab Diamonds, Natural Diamonds, Moissanite, and Cubic Zirconia - Exploring the Key Differences - A Full Guide

Introduction:

In the realm of gemstones, there exists a myriad of options, each possessing its own allure and distinct characteristics. Among the most popular choices for jewelry are lab diamonds, natural diamonds, moissanite, and cubic zirconia. However, navigating the differences between them can be daunting for the uninitiated. In this comprehensive guide, we delve into the unique attributes of each, shedding light on their origins, compositions, and visual properties.

1. Natural Diamonds:
• Origins: Natural diamonds are formed deep within the Earth's mantle under intense pressure and heat over millions of years.
• Composition: Comprised of pure carbon atoms arranged in a crystal lattice structure, natural diamonds boast exceptional hardness and durability.
• Characteristics: Renowned for their unparalleled brilliance, natural diamonds exhibit a unique play of light known as fire and scintillation.
• Rarity: Despite their widespread popularity, natural diamonds are relatively rare, making them highly coveted and valuable.
2. Lab Diamonds:
• Origins: Lab diamonds, also known as synthetic or cultured diamonds, are grown in controlled laboratory environments that mimic the natural diamond formation process.
• Composition: Chemically identical to natural diamonds, lab diamonds possess the same crystal structure and physical properties.
• Characteristics: Lab diamonds exhibit the same brilliance, fire, and durability as their natural counterparts, offering a more sustainable and ethical alternative.
• Accessibility: With advancements in technology, lab diamonds have become increasingly accessible and affordable.
3. Moissanite:
• Origins: Moissanite is a naturally occurring mineral discovered in meteorites, but most commercially available moissanite is lab-created due to its rarity.
• Composition: Composed of silicon carbide, moissanite possesses remarkable hardness and brilliance.
• Characteristics: Moissanite exhibits a fiery brilliance that rivals that of diamonds, with unique optical properties that create a distinct sparkle.
• Affordability: Moissanite is more affordable than diamonds, making it an attractive option for budget-conscious shoppers seeking a diamond alternative with exceptional sparkle.
4. Cubic Zirconia (CZ):
• Origins: Cubic zirconia is a synthetic gemstone created in laboratories using zirconium oxide.
• Composition: While visually similar to diamonds, cubic zirconia lacks the same hardness and durability, making it more susceptible to scratching and abrasion.
• Characteristics: Cubic zirconia possesses a high refractive index, resulting in intense brilliance and sparkle.
• Affordability: Among the most affordable diamond simulants, cubic zirconia offers a budget-friendly option for those seeking a diamond-like appearance without the hefty price tag.

Visual Comparison:

To illustrate the differences between these gemstones, consider the following visual cues:

• Natural diamonds and lab diamonds exhibit a similar brilliance and sparkle, with subtle variations in color and clarity.
• Moissanite boasts a distinctive rainbow-like sparkle, often characterized by vivid flashes of color.
• Cubic zirconia showcases a brilliant, albeit slightly less realistic, sparkle compared to diamonds, with a tendency to exhibit more pronounced flashes of color.

The making/crystallization of man made stones:

Lab Diamond Creation Processes:

1. Chemical Vapor Deposition (CVD):

• Preparation: The process begins with a small, flat substrate, typically a slice of diamond seed crystal, placed in a vacuum chamber. This substrate serves as the foundation for the diamond growth.
• Gas Mixture: A mixture of gasses, including methane and hydrogen, is introduced into the chamber. These gasses provide the carbon source needed for diamond growth.
• Activation: The chamber is heated to extreme temperatures, often exceeding 800°C, to activate the gasses and break down the methane molecules into carbon atoms.
• Diamond Growth: Carbon atoms precipitate onto the substrate, gradually forming a diamond crystal layer. This deposition process occurs layer by layer, resulting in the growth of a diamond with controlled thickness.
• Cooling and Inspection: Once the desired diamond size is achieved, the chamber is cooled, and the newly grown diamond undergoes rigorous inspection and quality assessment.

Example image of a CVD diamond growth machine:

Image Credit: Nex Carbon Technologies

Example image of a rough CVD diamond when fully grown.

Image credit: Shaanxi Speedin Jewelry

2. High Pressure High Temperature (HPHT):

• Seed Crystal: Similar to the CVD process, the HPHT method begins with a diamond seed crystal, which acts as a template for diamond growth.
• High Pressure Environment: The seed crystal is placed in a high-pressure press along with a carbon source, typically graphite, and a metallic catalyst, such as iron or nickel.
• Temperature and Pressure: The press subjects the materials to extreme temperatures (up to 2,500°C) and pressures (around 5-6 GPa*), simulating the conditions found deep within the Earth where natural diamonds form.
• Diamond Formation: Under these intense conditions, the carbon atoms from the graphite dissolve in the molten catalyst and precipitate onto the diamond seed crystal, facilitating the growth of a larger diamond.
• Cooling and Recovery: After the desired growth period, the press is cooled, and the newly formed diamond is recovered from the catalyst. The diamond is then cleaned, cut, and polished to enhance its brilliance and clarity.

Example image of a HPHT diamond press/tool:

Image credit: Henan Huanghe Whirlwind Co.

Example image of a rough HPHT grown diamond:

Image credit: Foshan Zhongchuan Precision Manufacturing Technology

Moissanite Production Process:

1. Chemical Vapor Deposition (CVD):

• Silicon Carbide Source: Moissanite is primarily composed of silicon carbide (SiC). In the lab production process, a silicon carbide source material, typically a mixture of silicon and carbon, is used.
• Gas Mixture: Similar to the CVD process for diamonds, a mixture of gasses, including silicon and carbon precursors, is introduced into a vacuum chamber.
• Activation: The chamber is heated to high temperatures, typically around 1,200°C to 1,600°C, to activate the gasses and initiate the deposition process.
• Moissanite Growth: Under controlled conditions, silicon carbide molecules form and deposit onto a substrate, gradually building up layers of moissanite crystal.
• Quality Control: Throughout the growth process, parameters such as temperature, pressure, and gas composition are carefully monitored to ensure the desired crystal structure and quality.
• Cooling and Processing: Once the moissanite reaches the desired size and quality, the chamber is cooled, and the crystal is carefully removed. The moissanite undergoes cutting and polishing to enhance its brilliance and clarity before being ready for use in jewelry.

2. Traditional Moissanite Manufacturing:

• Crystal Growth: In traditional methods, moissanite crystals were grown using the Lely process or the more modern sublimation method. These techniques involve heating silicon carbide powder to high temperatures and allowing it to crystallize into larger moissanite crystals over time.
• Cutting and Polishing: After the crystals are grown, they are cut into faceted gemstones using diamond saws and precision cutting tools. The rough moissanite gems are then polished to achieve the desired shape, brilliance, and clarity.

By employing these sophisticated processes, laboratories can produce high-quality lab diamonds and moissanite gemstones that rival their natural counterparts in brilliance, durability, and aesthetic appeal, offering consumers a sustainable and ethical alternative to mined gemstones.

Natural diamond, lab diamond, moissanite and CZ testing method and results:

When testing colorless (white) stones in general, there are two fast tools used worldwide. There are the standard “pen” testers and then there are “box” testers. The pen testers are the ones frequently seen at local jewelry stores and in online videos. They have a little probe that is used to check the thermal conductivity of the stone. This is done because diamonds have a specific thermal conductivity, making it possible to differentiate between diamonds and non-diamonds. The box testers, as the name suggests, are a box in which the diamond or piece of jewelry is placed. The box then uses specific lights to determine if a stone is either a diamond or not, and also if it is synthetic (lab-made) or natural.

Within both categories, there are cheaper and more expensive alternatives of the testers. However, in the case of box testers, they are usually all quite accurate. When it comes to pen testers, there are many cheap alternatives that will give false positives. Oftentimes, this makes it so a moissanite will test as a diamond. Thus, it is very important to be wary of the testers and the conditions they are in. We have dealt with jewelers whose testers were literally held together with duct tape, as they had fallen apart from years of use.

Image example of a pen tester:

Image credit: Presidium Instruments

Image example of a box tester:

Image credit: Presidium Instruments

When the different types of stones are tested in the testers, regardless of the type of tester, stones like Cubic Zirconia (CZ) usually have very limited heat conductivity and thus will either not test or give an error. When it comes to moissanite, it is a little different, as the heat conductivity of moissanite is higher, below the heat conductivity of diamonds, but much higher than CZ. This results in it being possible to test if a stone is moissanite, as they also have specific heat conductivity. For box testers, usually, if you try to test moissanite there, for the tester which tests for synthetic stones, the moissanite won’t test either, unless it is one of the more advanced testers, which give a full report of all stones put in the tester.

Lastly, there are the diamonds, both natural and lab-made. When tested on the pen testers, they should usually always or most of the time show as “diamond.” Sometimes, depending on the temperatures of a room or the environment in which the test is conducted, the result can be a false positive or false negative. Natural diamonds, for sure, should always show as diamond on the pen testers. However, for lab-made stones, there can be some slight discrepancies where they will show false negatives. This is why it is very important to either get a full lab report on the stones in your pieces or at least make sure that they have been tested in a box tester. The reason for this is that in a box tester, the diamonds will always test properly and show if they are natural or synthetic. However, other types of stones such as moissanite or CZ and other simulants will never test as a “diamond” in the box testers.

Please refer to our article here as well, regarding pen testers and lab diamonds:

Article Link (Click Here) 

Please note that this is taking into consideration mainly the more frequent testers, both pen and box versions, and not the very advanced ones, which are usually used by labs to always properly determine what stone they are dealing with.

Conclusion:

In conclusion, the choice between lab diamonds, natural diamonds, moissanite, and cubic zirconia ultimately boils down to personal preferences, budget considerations, and ethical concerns. While natural diamonds exude timeless elegance and rarity, lab diamonds offer a sustainable and affordable alternative. Meanwhile, moissanite and cubic zirconia provide dazzling options for those seeking maximum sparkle at a fraction of the cost. By understanding the unique characteristics of each gemstone, consumers can make informed decisions that align with their values and aesthetic preferences. Whether it's the enduring allure of natural diamonds or the eco-friendly appeal of lab-grown alternatives, the world of gemstones offers something for every discerning jewelry enthusiast.

Notes: