Opals are precious gemstones known for their mesmerizing play of colors and unique patterns. There are two main types of opals: natural and synthetic. Understanding the difference between these two types of opals is important for gemstone enthusiasts, collectors, and buyers.

Natural opals are formed naturally in the earth’s crust, usually over millions of years. They are made up of silica and water and can form in a variety of shapes and sizes. Natural opals are prized for their rarity and beauty, but they can also be more fragile and susceptible to cracking or breaking due to their delicate composition.

Natural Black Opal

Image 1: Natural Opal with irregualr patterns and colour zones

Synthetic opals, on the other hand, are created in a laboratory environment. Synthetic opals are made by recreating the conditions that naturally form opals, and they are typically made of resin or glass. Synthetic opals are less expensive than natural opals and are often used in jewelry or other decorative items. However, synthetic opals lack the beauty and rarity of natural opals and do not have the same value in the market.

Lab made opals raw

Image 2: lab made opal blocks

When it comes to appearance, synthetic opals can sometimes be difficult to differentiate from natural opals. Both types of opals can have a similar play of colors and patterns. However, synthetic opals often have a more uniform appearance and are less likely to have the unique inclusions eg sand, gypsum, natural host rock liek ironstone or fine fractures that can be found in natural opals. The consitency of the patterns and colors in synthetic Opals are the big clues to whether it is synthetic - the perfect aligned stripes and snake-skin pattern of colors are also a dead giveaway.

synthetic opal patterns

Image3: Synthetic Opal stripe and snakeskin patterns

Natural Opals will usually have zoned color areas, and inconsistent patterns over the whole Opal surface. Overly perfect stones tend to be synthetic due to the growth and manufacturing process in a very short time.   

Boulder Opal rocks

Image 4: Natural Boulder Opal with host ironstone

In conclusion, both natural and synthetic opals have their own unique characteristics and place in the market. Natural opals are prized for their rarity and beauty that makes it a high end jewellery gem, while synthetic opals are a more affordable alternative for costume or entry level jewellery. When purchasing an opal, it is important to know the difference between natural and synthetic opals to ensure that you are getting the gemstone that you want at the fair market value.

David van Niekerk