A Guide to Synthetic Gemstones: Are Synthetic Rubies and Sapphires “Real”? How They Differ from Natural Gems in Price and Value.

Synthetic rubies and sapphires are common in the jewelry market. They are produced in labs, not mined. That raises two questions people ask most: are they “real” gems, and how do they compare with natural stones in price and long‑term value? This guide explains the science, the practical differences, and what they mean when you buy or sell jewelry.

What “real” means: chemistry, origin, and jargon

When gemologists call a stone “real,” they usually mean it has the same chemical composition and crystal structure as the natural mineral. Both ruby and sapphire are varieties of corundum. Corundum is aluminum oxide, chemical formula Al2O3. A ruby is corundum colored red by chromium. A sapphire is corundum colored blue by iron/titanium, or other colors when different trace elements are present.

Lab‑grown (synthetic) corundum is chemically and physically the same as natural corundum. It has the same hardness (Mohs 9), the same refractive index (about 1.76–1.77), and the same specific gravity (~4.00). The difference is origin: natural gems formed in the earth over millions of years, while synthetic gems grew in controlled lab conditions over days to months.

Methods used to make synthetic rubies and sapphires—and why they matter

There are several growth methods. Each leaves telltale signs that gem labs and experienced cutters can spot.

• Flame fusion (Verneuil). Molten powder falls on a seed rod. Growth is fast and cheap. It often produces curved growth lines and tiny gas bubbles. These are clear indicators of synthetic origin under 10–40x magnification.
• Flux growth. A solvent melts natural materials at high temperature and allows slow crystal growth. Flux inclusions look like flux films, mica‑like platelets, or irregular reflective particles. Flux synthetics can mimic natural inclusions and are tougher to detect without advanced testing.
• Hydrothermal. High‑temperature, high‑pressure water dissolves nutrients and deposits crystals on a seed. Hydrothermal corundum can produce inclusions similar to natural stones, such as needle‑like growth features, but also often shows characteristic healed fractures and certain mineral inclusions.
• Czochralski (pulling) and other methods. Used less often for gem corundum but relevant for high‑quality synthetic crystals.

Why this matters: the method affects clarity, color distribution, and the types of inclusions. Those features influence price and detectability.

How synthetics compare to natural gems in appearance and performance

In most jewelry settings, a synthetic ruby or sapphire will look identical to a natural one. Under normal lighting and to the unaided eye, color, brilliance, and toughness are the same. That’s why synthetic stones are popular for fashion and commercial jewelry.

But under a microscope, differences appear. Natural stones often show irregular, two‑dimensional mineral inclusions, fingerprint patterns, crystallographic zoning, and evidence of metamorphic or magmatic growth. Synthetics tend to show growth features tied to the method used: curved striae (flame fusion), flux remnants, or specific trace element signatures.

Price differences: concrete examples and why they exist

Price varies by size, color, clarity, treatment, and origin. Here are typical price anchors to show scale. These are approximate and will vary by market and time.

• Small, commercial synthetic sapphire (1–3 ct): $20–$200 for a faceted stone or set stone in jewelry. These are often flame fusion and mass produced.
• High‑quality synthetic sapphire or ruby from hydrothermal or flux (1–5 ct): $100–$1,000 depending on color and clarity. These can be quite fine and aimed at collectors or precision instruments.
• Natural sapphire, commercial quality (1 ct, heat treated): $200–$1,500 depending on color and origin.
• Fine natural sapphire or ruby, untreated, good color and clarity (1 ct): $2,000–$20,000+. Burmese rubies or Kashmir sapphires can command much higher prices per carat.

Why the gap? Natural, high‑quality corundum is rare. Mining costs, supply constraints, and market demand drive prices. Synthetics can be produced reliably, so supply is not limited. That reduces their market price dramatically.

Value and resale: what to expect

Resale value is where synthetics and naturals diverge most.

• Synthetics: Low resale value. Because they can be reproduced, buyers will not pay a premium. You can expect little to no appreciation. Resale is often at a fraction of purchase price unless the synthetic has provenance as a historic lab sample.
• Natural stones: Better resale and potential appreciation, especially for stones with proven origin (Burmese ruby, Kashmir sapphire), documented untreated status, and certification. Rarity and market trends determine long‑term value.

Why this matters: if you buy jewelry as an emotional purchase or for everyday wear, synthetics offer excellent cost‑for‑look. If you buy as an investment, natural, certified, and well‑documented stones are the way to go.

Simulants and treated stones: different categories

Do not confuse lab‑grown corundum with simulants. Simulants mimic color but are different minerals: synthetic spinel, glass, cubic zirconia, or garnet. They have different hardness and optical properties and lower intrinsic value.

Treatments are also common with natural stones. Heat treatment is widespread and accepted. Diffusion, fracture filling, or dyeing reduce value and require disclosure. A natural ruby heat‑treated for color will be priced lower than an identical looking untreated stone with lab certification.

How to buy wisely

• Ask for a lab report. For stones >1 ct or for pieces you consider an investment, insist on a report from a reputable lab stating whether the gem is natural, synthetic, or treated. The report should list growth method or treatment and, when possible, origin.
• Demand disclosure. Sellers must disclose “lab‑grown” or “synthetic.” If they don’t, walk away.
• Compare with price examples. If a 2 ct “ruby” is priced at $100, it’s almost certainly synthetic or a simulant. If it’s $10,000, ask for documentation proving natural origin and treatment state.
• Consider purpose. For daily‑wear jewelry where cost and durability matter, a synthetic sapphire set in 14k gold (Au‑58.5%) is a great choice. For heirloom or investment pieces, prioritize natural, certified stones and higher‑karat gold (18k = Au‑75%) or platinum settings for permanence.

Bottom line

Synthetic rubies and sapphires are “real” in the sense that they are true corundum with the same physical and chemical properties as natural stones. They are not rare, however, and that makes them far less expensive and poor candidates for long‑term investment. Choose synthetics for appearance and affordability. Choose natural, documented stones when rarity, provenance, and resale value matter.