Fake Citrine is Natural Amethyst
How to Tell Heated Amethyst from Real Citrine
People are often surprised to learn natural citrine is relatively rare. Named after the French word "citron" meaning lemon, citrine is the yellow variety of the mineral quartz.
The vast majority of citrine being sold around the world is heated amethyst. The largest producer of "fake" citrine is Brazil and ironically they're also the world's largest producer of natural citrine.
Throughout history humans have copied and reproduced anything that's rare or highly sought after. With the advancement of technology it's now easier than ever to replicate almost anything.
Rocks and minerals are no exception and have been imitated for thousands of years. Turquoise is believed to be the first mineral to have been replicated. Fake turquoise has been found in ancient Egyptian tombs.
The ancient Greek philosopher Theophrastus noted many stones change colour when heated. He subsequently classified them according to the way they reacted to fire.
Ancient Roman author and naturalist Pliny the Elder also noted the effect that heat had on stones. In his encyclopaedia "Naturalis Historia" he wrote one gemstone can be changed into another. He also noted the colour of quartz could be changed into that of an emerald.
Heating Stones to Alter Colour
When amethyst is heated to 450°C (842°F) it starts turning yellow. Increase the temperature and it turns orange and then orange-brown. The final colour is determined by temperature and the length of time the material is heated. This is how "fake" citrine is produced.
Exposure to heat changes the chemical composition of amethyst which leads to a gradual reduction in the amount of iron. Impurities of iron are the primary reason for its purple colour.
Heat is widely used to enhance or change the colour of many minerals. It can also be used to remove unwanted characteristics such as a wisp of colour.
Almost all blue topaz is heated. Although it does occur naturally it's extremely rare. The colour of natural blue topaz bears little resemblance to the Sky, London and Swiss Blue gemstones produced through various heat treatments.
Most of the world's finest rubies and sapphires are heated. A ruby that's not been heated is extremely rare.
Aquamarine is also commonly heated to turn greener stones blue.
Despite heat treatments being an accepted enhancement, attitudes towards heated amethyst being sold as citrine seem to be shifting.
With natural citrine being relatively rare it tends to be quite expensive. For this reason amethyst has long been accepted as being the next best thing.
Heating changes the colour of a stone by interfering with its chemical composition. The process is similar to what happens in nature over millions of years.
Using heat to enhance or change the colour of rocks and minerals is not the same as dyeing them.
Agate and onyx are frequently dyed to make less interesting colours more desirable.
Fake Citrine What to Look Out For
Although there are exceptions, it's usually relatively easy to identify fake citrine. It's worth remembering the vast majority of commercial grade citrine is heated amethyst.
One of the most obvious clues is the presence of white or colourless quartz. In a rough crystal this will be visible towards the base.
A common characteristic of amethyst is colour zoning. When the stone is heated this characteristic doesn't change. A difference in the shade of colour will therefore be visible in fake citrine.
Colour is one of the easiest ways to identify amethyst that's been heated. Heated amethyst will often have a rich almost burnt orange colour. This can be more noticeable in lower grade or poorly produced stones.
Natural citrine can vary from light yellow to golden yellow to orange or can even be brownish yellow. Stones with subtle colour are far more abundant and less expensive than those with a more saturated and uniform colour.
Another clue to identify natural citrine is dichroism. Dichroism is a phenomenon whereby the colour of a crystal changes depending on the angle from which it absorbs light. Citrine is dichroic but amethyst is not.
The test is not always conclusive because some citrine is only slightly dichroic. Furthermore smoky quartz and some other quartz varieties can also be heated to produce fake citrine. Once heated they too can be dichroic.
So this test may confirm a stone is not heated amethyst but there's no guarantee it's natural citrine. The test is not easy test to carry out unless you know exactly what to look for.
Amethyst may not be dichroic but it is pleochroic. Minerals that exhibit pleochroism display different colours when viewed from different directions.
As a last resort to establish whether citrine is real you could try heating it. Natural citrine fades when heated. The problem with doing this is there's a 50/50 chance you're going to ruin what may be genuine stone.
What's in a Name?
I think the main issue with heating amethyst to produce fake citrine is some people quite rightly feel cheated. Heated amethyst is not citrine.
In the field of rocks, minerals and gemstones the practice of heating or dyeing stones is relatively common.
Dyed agate or chalcedony is often sold as black onyx. The vast majority of coloured or banded "onyx" is calcite. Blue topaz is white or colourless topaz that's been irradiated. Lemon quartz is produced by heating amethyst or pale citrine.
Smoky quartz can also be produced by heating clear quartz or citrine. Even natural citrine is often heated to enhance the colour.
Many stones have trade names that can be incredibly misleading because they do not reflect what the material actually is.
I have often wondered whether it would be more appropriate to call fake citrine yellow quartz but that presents a whole new set of challenges. Yellow quartz is basically natural citrine just as purple quartz is amethyst.
Since the 4th century BC the name amethyst has been synonymous with naturally occurring violet to purple coloured quartz. Therefore quartz crystals with any other colour cannot be called amethyst.
A relatively new material discovered in Patagonia in Argentina has been given the trade name pink amethyst. The name is contentious and tends to be used by those whose interest in rocks and minerals is metaphysical.
Some argue it should be called pink quartz but that's also problematic.
Rose quartz is the pink variety of the mineral quartz but there's another type of rose quartz often referred to as pink quartz. This material is far more scarce and has a slightly different chemical composition.
Pink quartz fades when exposed to sunlight and also forms individual crystals.
The colour of rose quartz is stable and its crystal habit is massive. This means crystals form as one large intergrown mass so have no external shape or structure. Individual crystals in rose quartz have never been found.
Despite being scientifically incorrect, this is likely to be the reason why the name pink amethyst was chosen for the new material from Argentina.
Different types of quartz have different names because their chemical composition varies often because of impurities.
The material known as pink amethyst has a different composition to amethyst, rose quartz and the variety known as pink quartz.
Prasiolite is a rare green variety of quartz. Most commercial grade prasiolite is heated amethyst. It's often marketed as green amethyst. Amethyst cannot be green!
Something else to be aware of is citrine very rarely occurs as a geode. The citrine geodes being sold commercially are amethyst that's been heated often in industrial sized ovens. The crystals often have that burnt orange colour.
What's Madeira Quartz?
Madeira quartz is a trade name that I think has only recently been introduced.
It's clearly been taken from Madeira citrine.
Madeira citrine is a trade name for natural citrine with deep saturated colour. The finest grade stones are rich golden-reddish-brown. The name comes from the Portuguese fortified wine from Madeira because of the similarity in colour.
I have however recently seen the name being used to describe darker coloured fake citrine.
Although there's a tendency to shy away from fake citrine its production serves a purpose.
Heating amethyst to produce this yellow variety of quartz provides consumers with the opportunity to purchase a similar looking stone at a more affordable price.
Heated amethyst should always be cheaper than natural citrine.
Buying fake citrine can also be a more sustainable option because of the rarity of the natural stone. When demand is high for a mineral there's a significant risk of it being over-mined. Ocean jasper is a perfect example.
Despite being labelled "fake" citrine it's important to remember this crystal is natural amethyst. When well produced it can really be very nice.
Tumbled stones can be exceptionally colourful and can exhibit subtle iridescence.
With regards to fine grade gemstones, the level of skill and expertise required is the same whether the stone being faceted is heated amethyst or natural citrine. With both being varieties of quartz their hardness is the same.
Is Heated Amethyst "Fake" Citrine?When referring to heated amethyst as citrine terminology is important. Although often described as "fake" or "imitation" citrine neither word is particularly appropriate.
We've used them here because both are commonly used. They don't tend to be used by retailers because heated amethyst is widely accepted as being an alternative to natural citrine.
It's worth remembering the vast majority of blue topaz started off as clear or white topaz. After being heated it doesn't become known as fake or imitation blue topaz.
Clear quartz that's been heated to produce smoky quartz is never called fake or imitation smoky quartz.
In my mind fake or imitation citrine would be glass, resin or some other man-made material, not a natural stone that's been heated.
When a stone that's been altered or enhanced is being offered for sale a customer should always be made aware of what they're buying. There's nothing in law however that requires a retailer to do this.
The correct terminology at least for the time being for citrine that hasn't occurred naturally should be heated amethyst.
"Heat treated citrine" is sometimes used but can be misleading because natural citrine is often heated to enhance the colour.
In North America the term "baked" or "cooked" amethyst is often used.
The tumbled stones in our final two photos are natural citrine. The darker stones come from the Democratic Republic of Congo, the lighter stones from Zambia.
The heated amethyst tumbled stones and three rough "citrine" crystals come from our collection.
The retailer holding a handful of "natural untreated rough fine grade citrine crystals" comes from a listing on a popular online marketplace.
The photo of the pink amethyst geodes is courtesy of Bob Harman (FMF Minerals Forum). The photo is clickable and redirects to the original image which is worth seeing.
The citrine geode is being offered for sale by a UK based online business.
The heated amethyst (citrine) cut gemstone is from our collection.
The natural citrine tumbled stones in our last two photos come from our collection.