Ethiopian Opal was discovered in 1990 but was first commercially mined until 2008. I remember when you could find small batches of these opals at the Tucson Gem and Mineral show in the mid-90s. Some gemstone dealers were trying to pass them off as Australian opals while others were upfront with where they came from but they wanted Australian opal prices.
At the time, buyers were not interested in paying high prices and people were questioning the stability of the Opals because they were cracking.
For example, buyers would purchase the Opals when they were wet but when you dried them out the Ethiopian Opals would start to crack, ruining the stone and its value. We’ve come a long way since the mid-90s and Ethiopian Opals have found their place in the Opal market.
Without further delay, let’s jump into and explore Ethiopian Opals
Types of Ethiopian Opal
There are a few different types of Ethiopian Opal, but I will be focusing on the most abundant and popular varieties. If you’re wondering where these Opals come from then you’ll be glad to know they’re sourced in the northern Welo District of Ethiopia.
If you’ve never seen this variety of Opal then you’re in for a surprise because Ethiopian Opals have huge color flashes and tons of “play of color”. I think it resembles a cross between Australian Opal and Mexican Fire Opal.
Black Ethiopian Opal
This Ethiopian Opal variety is usually very dark in color but it doesn’t have to be a solid black. As you can see from the image above, some of the cabochons have a dark grey tint to them. These are still considered black Opals.
If you’re looking to purchase a black Ethiopian Opal then you want to focus on the color red. The more red flashes you have in the stone the better but make sure the color flashes occur in the middle of the cabochon. If it’s on the edges or you have to roll the stone to a crazy angle to see it, then not as valuable.
Welo Ethiopian Opal
Welo Opals are considered precious and are from the Welo Province of Ethiopia. Many specimens are considered Fire Opals because of their orange, yellow, or red body color and the intensity of color.
Rare specimens are called Honeycomb Welo Opals because they display a honeycomb pattern. Don’t worry these are easy to spot but you don’t want to be tricked by a synthetic. When looking at the Opal up close you’ll notice a honeycomb pattern (no two honeycombs should be identical, if so be careful) in the stone and when you roll the stone those honeycombs will flash different colors at your eyes. These beautiful stones offer pastel colors ranging from pink, orange, blue, and green.
If you’re dealing with synthetic Opal then you’ll also see a honeycomb pattern but each comb will be identical in size and shape.
Ethiopian Fire Opal
These incredibly stunning Opals offer a bright orange to red body with flashes of rainbow fire. They are a variety of mineraloid Opal that produces a distinct appearance compared to other types of Fire Opals. For instance, the Australian Fire Opal isn’t as bright or colorful as this variety. However, they share similar properties.
How To Stabilize Ethiopian Fire Opal
Ethiopian Opal can be very unstable and that is why you’ll see it offered to buyers in a tray or vial of water. You need to ensure the stones won’t dry out and crack on you before you purchase. Let’s dive in on the process of stabilizing Opals.
Clean & Prepare Your Specimen
We must use caution when cleaning Ethiopian Opals to help preserve the material as much as possible.
Grind or file off the matrix surrounding the Opal using as little water as possible. You’ll want to wear a mask and do this outdoors. Usually, this process involves more water, but not with these stones. Flat files work best or you can use a dremel with 220 grit. While we don’t want the stone in water, the file can be dipped to keep the dust down.
Once the grinding or filing is done, remove the dust from the stone’s surface, leaving it as open as possible. Microfiber cloths are excellent for this task. If you used water during this process, ensure the clarity hasn’t changed. If it has, the specimen needs time to dry.
Prepare The Stabilizing Mixture
This is epoxy that hardens when the two compounds are mixed; both are soluble in acetone. Due to the volatile compounds known as carcinogens, you will need a respirator when making the mixture indoors.
You will want one standard syringe of two-part 330 epoxies for every liter of acetone. Pour the acetone into a bottle or jar and slowly add the epoxy while using a wooden stick to stir. No metal or plastic because there’s a risk of an adverse reaction.
Once your solution is ready, drop the Opals in and close the jar. Leaving the jar open will cause the acetone to evaporate, leaving behind a hard resin that traps the Opals.
Let It Soak
Your Opal must be left in the covered jar for six to eight weeks. This allows the epoxy to work deep into the stones.
Let It Dry
Get a Pyrex or baking pan, set it somewhere dry, and bring your jar over to it. Use a gloved hand or long tweezers to retrieve the stone from the mixture. If you have more than one Opal, spread them out so there’s a bit of room.
Leave the stones alone to airdry for about a week. You will need to turn them over once daily to help keep the amount of epoxy between the stone and dish smaller. If your stones stick to the pan, use a thin knife or razor blade to dig into the acetone. Cut through the epoxy; don’t pry it away.
Once the stones are dry and stabilized, they’re ready to cut. Take the typical precautions when cutting Opals since the silica is rough on the lungs. If you hit a wet spot while cutting, stop and allow the stone to dry out before proceeding.
You can keep the remaining mixture or discard it. However, if the mixture is discolored, it’s best to toss it.
To dispose of this mixture properly and safely, contact the local landfill to find the nearest HAZMAT disposal area. If there isn’t a location close enough, place the mix outside on a bright sunny day to let the acetone evaporate. The mixture will harden into a non-reactive resin that can be discarded in the garbage. You’ll know it’s safe when the jar is dry and doesn’t smell of solvents.
Ethiopian Opal In Water
Ethiopian Opals are often hydrophane Opals with large pores that absorb water. This makes the Opals less stable, especially for cutting.
Only rough material can be stabilized.
Why Does Ethiopian Opal Turn Yellow?
The stone’s ability to absorb water and liquids causes the stone to change to a translucent yellow or brown. The play-of-color will disappear temporarily but it returns when the stone is dry.
Fake Ethiopian Opal
Let’s get down to it.
- Fake Opals or synthetics are usually too perfect and look man-made.
- Turn the specimen on its side and look for straight columns of color that run vertically; this is a sign of a fake Opal.
- If the stone is perfectly oval or round, it’s likely a fake.
- Study the honeycomb structure inside the stone while it is facing up. You’ll notice the pattern of identical honeycombs, all the same size.