Dyed stones, heat-treated minerals, reconstituted amber and turquoise being sold as the real thing - and in some cases, cheap minerals being sold as more expensive look-alikes.
Dying or altering or minerals is not necessarily wrong - up until the moment the dealer tries to scam the customer into believing that it's a natural stone, not a man-made object.
In most cases, when I asked, the dealers assured me that these fakes were, of course, completely natural and unaltered. Some of them may have thought they were telling the truth, I don't know. But as a mineral collector, it is becoming more and more important to know exactly what you are buying, and how to identify the scams.
I thought I'd give a brief overview of some of the most common fakes I saw.
The majority of the 'citrine' you'll see being sold is actually amethyst which has been heat-treated to change the color from purple to yellowish brown.
True citrine is almost never orange-tinted. It is lemon-yellow, or even a bit greenish. And I have never seen it in geode form. If it's in a geode or crystal vug, it's probably amethyst. Real citrine crystals tend to be longer and slenderer than fake ones, which are usually short and stubby. And fake citrine is usually very colored at the tip, fading to white at the base.
Another clue is price. True citrine is a valuable and rare gemstone, and it's very unlikely you're going to find it tossed around in the bargain bin at a rock show.
Here is an excellent post on distinguishing between the two, with photographs.
|Fake Citrine - the patchy color is a giveaway|
Tiger's eye is usually brown/gold in color. Sometimes you will find reddish pieces [in Tiger Iron, for example] but if it's natural, it'll likely only be a small reddish streak or patch in an otherwise normal-colored piece. Fully red specimens have been heat treated to create the color.
There's a variety of blue-gray tiger's eye, called hawk's eye, but it is rarer than the gold color. Beware when buying blue, because it is often dyed rather than natural. If it's a particularly bright blue rather than gray-blue, it's probably fake.
Bright green tiger's eye is dyed. Don't ever believe green tiger's eye.
|Dyed green Tiger's Eye|
Most of the agate jewelry and slabs you will see have been dyed - brilliant greens, yellows, blues or pinks. True agate is generally more muted in color. If the quartz crystals in the center of an agate slab are colored, it's probably dyed. And dyed agate bands usually seem more blurred than the naturally-colored pieces. If there's a whole bunch of complete different colors all being sold in the same case, they're probably all fakes.
Aurora Borealis Coating:
This is a synthetic coating, the same stuff that gives rhinestones their glitter. It's used to make mineral specimens more sparkly and colorful. When asked, the dealer selling A.B.-coated aquamarines insisted that they were "totally untreated!". It was only when confronted with the little note of "AB" on the label, that she finally fessed up.
|Fake sparkles on real rocks|
Turquoise is another popular fake. Much of what you'll see sold as turquoise is plastic, howlite coated in blue dye, or lumps of plaster. Sometimes it'll be real turquoise dust, glued together into a lump.
Always ask where the turquoise came from, and if the dealer can't give a convincing answer, don't buy it. It should not be patchy white, like the photo below, although it may often have black lines running through it. It should be opaque, not translucent.
|Fake turquoise with a bad dye job|
"Peacock ore" is another name for the mineral Bornite, but most of what you'll see at rock shows is actually chalcopyrite which has been chemically treated to bring out the rainbow-colored effect.
Fake amber is, fortunately, not too hard to identify once you know what to look for. Commonly what you'll see is reconstituted amber, where scraps have been melted down and re-formed. This treatment is made obvious by circular, dish-shaped fractures within the material. Real amber rarely has any interior fractures, and certainly is not filled with them.
The other common scam is fake insects within the amber - if you see a piece that has a single, perfectly laid out dragonfly in dead center, assume it's fake - unless it's in a museum somewhere.
Remember, the bugs in amber were stuck in tree sap, and you can see that they were trying to escape - they'll have broken wings, be twisted at odd angles, and generally LOOK like bugs trying to get out of tree sap. Also, there's usually a bunch of debris in any piece of amber. If there's one large bug and no smaller ones, bits of leaves, broken off wings, or dirt, be suspicious.
Want more information about fake mineral scams? Try this site.