I think the best place to start is to learn how one goes about restoring a fossil in the first place.
I like to call restoration nothing more than putty and paint. It's so easy that anyone can do it and that is where the problems begin. Anyone can paint a picture but very few can do it well enough that you actually want to "buy" their painting. Even an elephant in Thailand can paint you a picture.
But we still need some putty. In order to restore a fossil we need some type of material that is going to take the place of the area that was missing in the first place. Paleosculp is often used in this regard. It's a two part mix that has the feel and texture of modeling clay. You mix them together in equal parts and begin to use this material to sculpt the missing area, which gives you a few hours of working time before it begins to harden. Anyone can do it....but very few can do it well.
What you need next is pretty basic...a couple paint brushes.
And some paint.
And WALA...for less than $100 in supplies you are now a Professional Fossil Restorer. You don't need any kind of formal education...you don't need a fancy certificate...and you don't even need to be good at it. Just get yourself some beat up and banged up junky fossils for the lowest prices you can find...start adding some sculpting bond...slap on some paint...and off you go! The more beat up the tooth is....the cheaper you will be able to buy it...and the more profit you will be able to make. Sad but true.
But don't get my wrong...there are a few...and I mean just a few....very talented artist out there that do amazing restoration work and they deserve all the praise I can possibly give them.
But only half the problem with restoration is the fact that it is being done by people with absolutely no talent whatsoever. The other half of the problem is that fossils in general often times get traded or resold over and over again for reasons to varied to get into here. Perhaps collector "A" sales his restored tooth to collector "B" with full disclosure that the fossil was in fact restored. But now collector "B" needs a new radiator and decides to not disclose the restoration to collector "C" in order to get more money. And now the true identity of this restored fossil is lost and traded or resold over and over again....until someone spots it. And the cycle potentially repeats itself over and over again...with thousands of restored fossils in the market place.
But enough of that...let's see if we can figure out how to spot restoration.
Step 1) Just look at the tooth. As mentioned above, 95% of Restoration out there is pure garbage and can easily be spotted by a 5 year old. In the end..the tooth has to be painted and even the most skilled artist has a very hard time matching up paint to what mother nature has created.
A good rule of thumb for restoration is "you should be able to hold the tooth or other fossil out in front of you at arms length and NOT notice the restoration."
Step 2) View the suspected area under a microscope.
The microscope above will do the trick and is very inexpensive. You absolutely do NOT need some fancy expensive microscope to get the job done. I see the above on Amazon for around $10 with free shipping, and I would put a link here but I don't want anyone thinking I am trying to make .03 cents per microscope and therefore this blog post is a money grab. These are about the size of your thumb and for some people with bad eyes you might just want to go with a larger magnifying glass. Both will do the trick. You will be very surprised how much you can see with a cheap little microscope like this.
What you are looking for is paint and/or paint strokes. What will that look like you ask? You will notice it when you see it. Real enamel has depth to it and paint....well paint simply lays on top of a surface. But you do need to put this tiny scope directly on the object. Don't try to hold it 6 inches or even 1 inch away from the suspected area. You need to be touching the end of those scope onto the area.
And you don't need to be an expert or really even have any experience at all looking for restoration. As soon as you see paint...you will have an "Ahh...Haa" moment. If you see paint...you can stop here. If you just aren't sure what you are seeing then go onto the next step.
Step 3) Acetone and a paper towel - super high tech.
Acetone can be picked up at just about an hardware store or Walmart.
This next step is very important. YOU WANT TO START OFF WITH JUST A DAB OF ACETONE. And the reason I say this is because if you do find undisclosed restoration and you want to return the tooth and get your money back, the seller might say you ruined the tooth if you go rubbing all the paint off of it. So start off small. You won't need much. You aren't looking to expose all of the restorers work. Your just looking to get enough paint on the paper towel to confirm there is paint on the tooth. No Natural tooth comes with paint. Only a restored tooth. So you only need the smallest amount to show up on your paper towel for confirmation.
Acetone is nothing more than paint thinner (remover). Just put a small dab on the paper towel and lightly...LIGHTLY I SAID...go over the area of the tooth in question. Acetone will do NOTHING to a 100% Natural fossil. So you do not need to fear ruining a perfectly good tooth. You could soak a natural tooth in Acetone overnight and pull it out the next day and it would have done nothing to the tooth.
If you see paint on the paper towel....bingo...you have a restored tooth! If you see no paint...you can put a little more acetone and rub a little harder. If still nothing than the tooth is Natural.
And on a side note, the serrations are a good place to start when viewing a restored tooth online. Very few artist can do good work when it comes to the serrations. In fact, terrible restorers are so sloppy and lazy that they will restore one whole side of the blade and not even bother to put any serrations on it. Why? They either don't know how...or they feel it is to time consuming and they just want to "pump and dump" these fossils out the door. This is a sure sign of terrible restoration work.
I hope this blog post has been helpful. Feel free to comment below if you have any added tips or tricks to spotting restoration work. I didn't mention using a black light because in many cases it is useless. Just depends on the material they used to restore the tooth with and the paint they are using as well.