{"id":328,"date":"2026-06-29T07:41:46","date_gmt":"2026-06-29T07:41:46","guid":{"rendered":"https:\/\/www.usajewels.com\/blog\/index.php\/2026\/06\/29\/how-diamond-simulants-compare-to-real-diamonds\/"},"modified":"2026-06-29T07:41:46","modified_gmt":"2026-06-29T07:41:46","slug":"how-diamond-simulants-compare-to-real-diamonds","status":"publish","type":"post","link":"https:\/\/www.usajewels.com\/blog\/index.php\/2026\/06\/29\/how-diamond-simulants-compare-to-real-diamonds\/","title":{"rendered":"How Diamond Simulants Compare to Real Diamonds"},"content":{"rendered":"<\/p>\n

A diamond simulant is a gemstone designed to replicate the appearance of a real diamond but without sharing its chemical composition or physical properties. Understanding how diamond simulants compare to real diamonds is the single most important step before buying an engagement ring or any fine jewelry piece. The industry term for these stones is \u201csimulated diamond,\u201d and it covers materials like cubic zirconia and moissanite. Lab-grown diamonds are not simulants. They are real diamonds grown in a laboratory, with the same carbon crystal structure as natural stones. Knowing that distinction protects you from costly misunderstandings.<\/p>\n

How do diamond simulants differ from real diamonds chemically and physically?<\/h2>\n

Real diamonds consist of pure carbon atoms arranged in a cubic crystal structure. That structure is what gives diamonds their legendary hardness and optical brilliance. Simulated diamonds mimic diamond appearance<\/a> but lack that carbon composition entirely. They are made from completely different materials.<\/p>\n

The two most common simulants are cubic zirconia and moissanite. Cubic zirconia is made from zirconium dioxide. Moissanite is made from silicon carbide. Industry and legal standards<\/a> require pure carbon crystalline structure for a stone to be called a diamond. Neither simulant meets that standard.<\/p>\n

\"Gemologist<\/p>\n

Lab-grown diamonds, by contrast, are chemically and physically identical to natural diamonds. They are real diamonds, just grown in a controlled environment rather than mined from the earth. You can read more about the differences in this lab-grown vs. natural diamond guide<\/a> from Usajewels. Standard diamond testers detect the difference between simulants and real diamonds by measuring thermal and electrical conductivity, properties that vary significantly between these materials.<\/p>\n

Pro Tip:<\/strong> Never assume a stone is real simply because it looks flawless. Flawlessness is actually a common trait of simulants, not natural diamonds.<\/em><\/p>\n

What are the differences in hardness and durability?<\/h2>\n

Hardness determines how well a stone resists scratches and daily wear. The Mohs hardness scale rates minerals from 1 to 10. Natural and lab-grown diamonds score 10, the highest possible rating. Moissanite scores approximately 9.25. Cubic zirconia scores between 8 and 8.5.<\/p>\n\n\n\n\n\n\n\n\n
Stone<\/th>\nMohs Hardness<\/th>\nDaily Wear Durability<\/th>\n<\/tr>\n<\/thead>\n
Natural diamond<\/td>\n10<\/td>\nExcellent, resists scratching<\/td>\n<\/tr>\n
Lab-grown diamond<\/td>\n10<\/td>\nExcellent, identical to natural<\/td>\n<\/tr>\n
Moissanite<\/td>\n~9.25<\/td>\nVery good, minor scratch risk<\/td>\n<\/tr>\n
Cubic zirconia<\/td>\n8\u20138.5<\/td>\nModerate, clouds and scratches over time<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Those numbers have real consequences. Cubic zirconia worn daily in a ring will develop surface scratches and a cloudy appearance within a few years. Moissanite holds up better but still falls short of diamond\u2019s permanence. For an engagement ring worn every day for decades, that gap matters.<\/p>\n

Simulants are also more prone to chipping under hard impact because their crystal structures are less tightly bonded than diamond\u2019s. A diamond ring can survive a knock against a countertop that would chip a cubic zirconia stone. For occasional wear pieces like fashion jewelry or travel accessories, that trade-off is entirely acceptable. For a piece meant to last a lifetime, it is worth weighing carefully.<\/p>\n

\"Infographic<\/p>\n

Pro Tip:<\/strong> If you choose moissanite for daily wear, have the setting inspected annually. The stone\u2019s slightly lower hardness means prongs can loosen faster than they would with a diamond.<\/em><\/p>\n

How do optical properties and visual performance compare?<\/h2>\n

Sparkle is where simulants genuinely shine, sometimes too much. Real diamonds have a refractive index of approximately 2.41<\/a>. Moissanite\u2019s refractive index is approximately 2.65, which produces stronger fire, the rainbow flashes of color you see when light passes through the stone. Some simulants have color dispersion more than four times that of diamonds. That sounds appealing, but trained eyes notice it immediately.<\/p>\n

Here is how the key optical properties stack up:<\/p>\n\n\n\n\n\n\n\n\n
Property<\/th>\nNatural Diamond<\/th>\nMoissanite<\/th>\nCubic Zirconia<\/th>\n<\/tr>\n<\/thead>\n
Refractive index<\/td>\n~2.41<\/td>\n~2.65<\/td>\n~2.15<\/td>\n<\/tr>\n
Fire (color dispersion)<\/td>\nModerate<\/td>\nVery high<\/td>\nHigh<\/td>\n<\/tr>\n
Brilliance<\/td>\nHigh<\/td>\nHigh<\/td>\nModerate<\/td>\n<\/tr>\n
Typical clarity<\/td>\nInclusions common<\/td>\nEye-clean<\/td>\nFlawless<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

A few visual clues help you tell them apart:<\/p>\n