A ring with a sparkling stone, stud earrings set with deep blue topaz, a garnet pendant: gemstones give a piece its character. But what exactly separates a diamond from a brilliant, what is cubic zirconia, and what should you know about synthetic stones? This guide gives you an honest overview.
Diamond or brilliant: what is the difference?
A diamond is the material itself: crystallised carbon and, at 10 on the Mohs scale, the hardest natural mineral. A brilliant is a diamond in a particular shape, the round brilliant cut with 57 facets (58 if the tip at the bottom is polished as a tiny facet). This cut returns light in a way that makes the stone sparkle especially vividly.
Worth knowing if you buy in Germany: the word „Brillant“ on its own is reserved for diamonds. A cubic zirconia or glass stone in the same cut may not simply be sold as a brilliant; it needs a clear description such as „cubic zirconia, brilliant cut“.
The 4 Cs: how is diamond quality judged?
Four criteria have become standard for diamonds, named after their initial letters:
- Carat (weight): one carat equals 0.2 grams. Small stones in jewellery often weigh just a few hundredths of a carat.
- Colour: the more colourless, the rarer. The common international scale runs from D (exceptional white) to Z.
- Clarity: how many inclusions are visible under tenfold magnification? Typical grades are IF (internally flawless), VVS, VS, SI and P or I (inclusions visible to the naked eye).
- Cut: proportions and symmetry decide how much a stone sparkles, which often matters more than a few hundredths of a carat.
On jewellery made in Russia you may see markings such as „Кр57 3/4“. „Кр57“ stands for the round cut with 57 facets, while the numbers give colour and clarity groups under Russian standards. These scales do not translate one to one into international grades, so if a marking is unclear, it is better to ask than to guess.
What is cubic zirconia?
Cubic zirconia is a laboratory-made crystal of zirconium dioxide. It is very affordable and, in a brilliant cut, sparkles remarkably brightly. With a Mohs hardness of around 8 to 8.5 it is fairly tough, though clearly softer than diamond. Over years of daily wear its edges can pick up fine scratches, and grease or soap residue will make it look duller, so gentle, regular cleaning pays off.
By the way, zircon is something else: a natural mineral. The names sound alike, the stones are not.
Synthetic, natural or imitation?
A synthetic stone has the same chemical composition and crystal structure as its natural counterpart but was grown in a laboratory. A synthetic sapphire really is corundum; it simply did not form in the earth. In the trade it must be declared as synthetic, and the same applies to lab-grown diamonds.
An imitation, on the other hand, only looks similar and is made of a different material, such as glass or cubic zirconia standing in for diamond. Both are perfectly fine as long as they are named honestly. Many stones are also treated, for instance heated or irradiated to improve their colour. Such treatments are common practice in the trade and must be disclosed.
Popular gemstones at a glance
| Stone | Colour | Mohs hardness | Care note |
|---|---|---|---|
| Topaz (e.g. London Blue) | colourless, light blue to deep teal blue | 8 | avoid knocks, it can cleave; London Blue is usually colour-treated |
| Amethyst | purple | 7 | do not keep in strong sunlight for long, it can fade |
| Garnet | mostly dark red | 6.5–7.5 | easy-going, clean with lukewarm water |
| Sapphire | mostly blue, other colours too | 9 | very tough, ideal for everyday wear |
| Ruby | red | 9 | very tough, ideal for everyday wear |
| Emerald | green | 7.5–8 | brittle and often oiled: no ultrasonic cleaner, no heat |
| Onyx | black | 6.5–7 | the black is usually dyed; avoid acids and cosmetics |
| Pearl | white, cream, pink, grey | 2.5–4.5 | last on, first off; keep away from perfume and hairspray |
| Opal | milky with play of colour | 5.5–6.5 | contains water: avoid heat and very dry air |
| Swarovski crystals | many colours | approx. 6 | cut glass, can scratch; wipe with a soft cloth |
| Turquoise | sky blue to greenish | 5–6 | porous: do not soak, only wipe with a slightly damp cloth; no creams or oils |
Mohs hardness is a rough guide to scratch resistance. Natural stones vary, which is why ranges are given. You will find more detailed advice in our jewellery care guide.
Which stone belongs to which month? Birthstones
Birthstones make a lovely gift idea. There are, however, several lists that differ by country and tradition. A widely used modern list looks like this:
- January: garnet
- February: amethyst
- March: aquamarine
- April: diamond
- May: emerald
- June: pearl (also moonstone, alexandrite)
- July: ruby
- August: peridot (also spinel)
- September: sapphire
- October: opal (also tourmaline)
- November: topaz (also citrine)
- December: turquoise (also tanzanite, zircon)
Discover gemstone jewellery at IONN
Whether you prefer sparkling cubic zirconia or a coloured gemstone, browse our rings, especially the women's rings, as well as our earrings and pendants. To keep your stones looking their best for years, take a look at our care guide.