The artifact world is fraught with reproductions.  To combat this some collectors and dealers have sought out second opinions from those generally thought of as having sufficient expertise in the collecting field to be able to offer a paid opinion of the authenticity of an artifact.  These people are known as authenticators to the collecting world.  Most mean well, do their best to give an honest reporting, and all are self-taught and self-professed experts. There isn't a school capable of teaching a person how to identify fraudulent artifacts from non-fraudulent artifacts other than the school of hard-knocks.  Even a degree in Anthropology or Archeology can't teach a person what is learnable only from hands on experience.  All of them have their own methods for identifying reproductions from authentic points.  Most of them involve some kind of visual examination of the object for mineralization called PATINA by collectors.  Patina is the by product of the natural application of dissolved ground deposits such as lime-scale, iron, and other minerals carried onto the surface of an artifact over hundreds or thousands of years through ground water and decaying vegetable matter.  Over time it becomes part of the material of the artifact and is difficult (not impossible) to replicate.Patina gives an artifact a true aged look only time can produce. It might be called the fingerprint of authenticity. 

Every authenticator has their own method of identifying patina.  Most use some kind of visual examination such as an ultra-violet light and lighted magnification such as stereo-microscope, and even the physical feel of the artifact itself.  New artifacts often feel new, have sharp spots that time would have normally worn dull, and generally have a surface polish that doesn't feel old. Re-worked or re-chipped flint artifacts will have inconsistent feeling edges on them going from sharp to crushed feeling.  Stone axe bits should drag along a fingernail and feel scratching, reproduction axes will often be glass smooth and feel like talcum powder on the fingernail.  Ancient pottery shouldn't feel rock hard like new pottery will, and pottery with restoration will often have a dull, clay feeling to it in spots and smell like glue.  All of these methods are useful in some cases, but none-of-them are foolproof.  Where ultra-violet light is useful for spotting some freshly re-chipped flint edges on some types of lithic materials (not all) and may show streaks of copper left by a modern knapping tools, it often fails to identify old patina from new patina.  The most famous example of this was the Ossuary of the apostle James recently brought to light in which it was reported to contain the words, James-son of Joseph-brother of Jesus.  Only a stereo-scope was able to spot small microscopic shells contained in newly applied patina which proved the source of the calcium used was chalk and not dissolved minerals and proved some of the words were later inscriptions and the ossuary was a hoax.  Where stereo-scopes are useful in seeing mineralization, they probably will not show modern copper and are difficult to use.  More often or not, they are misused and too much magnification is applied which causes the person to look into the stone rather than onto its surface.  When this happen natural stone material is often mistaken for the presence or absence of mineralization. 

So what is the purpose of authentication?  Too often it is only a feel good expense for the buyer.  Dealers use it only as means to demand a higher price for their artifact and to make an easier sale.  In every case the only person who profits from it in the long run is the authenticator.  Some make nearly 3/4 of a million dollars a year providing opinions. Regardless, the buyer pays for it either directly or indirectly.  You are paying for an opinion - and only an opinion - which doesn't make the artifact any more or any less authentic than the next one.  Every authenticator has a clause in their authentication service stating this is only their opinion and absolves them from lawsuit should they make a mistake.  To put it bluntly, they only put YOUR money where THEIR mouth is and not their own. Authenticators play on the laziness of people to learn how to identify good artifacts from bad artifacts, the collectors paranoia, and their ego to demonstrate to the world the authenticity of their collection by flashing frames of certificates.  If this is your thing, great!  But all authenticators make mistakes. No one knows everything about anything, and not all artifacts patina the same way or can be tested the same way.  There are far too many variables in temperature, rainfall, and burial conditions around the world for anyone to become proficient in authentication of all artifacts. Even the great Sutherby Auction House found itself embroiled in scandal when it was learned millions of dollars worth of artifacts they certified later turned out to be fraudulent.

The authentication is only as good as the reputation of the person who provides it.  All issue a certificate of authenticity, and all get paid if the artifact is or is not authentic in their opinion.  Some even get paid twice by issuing so called kill letters if they believe an artifact is fraudulent - once for examining the artifact and again for issuing the letter at owner's request and expense.  Supposedly a kill letter ensures the artifact won't be authenticated by someone else later - as if the owner/seller won't throw it away, wait a few months, keeping the artifact out of sight, then sending it onto the next expert in hopes they approve it.  Eventually, someone probably will.  You can not get all authenticators to agree on an item.  Someone will always have a different opinion. 

Gregory Perino was at one time considered the ultimate expert in artifact authentication.  His services and certificates of authenticity were sought after by millions.  Now he is deceased, his certificates have been reproduced to the point they are nearly considered worthless, so what was the long term reasoning in adding another 30 dollars to the cost of an artifact with the certificate of authentication has become shunned by the collecting community virtually overnight?  One mistake can turn all the paper issued by an authenticator worthless in seconds.  

The best thing a collector can do is take the time to learn how to identify gmost ood artifacts from bad artifacts.  It is YOUR collection and the only person you need to make happy is YOURSELF.  Paper makers come and go.  They get rich from your laziness and ignorance.  Instead of spending money to make someone else rich, spend it on a good artifact.  You will build your collection faster, with much less cost, and be a whole lot happier with it and yourself than if you spend a great deal of your time chasing down opinions that will be one day worthless.  Artifacts last for eons - paper doesn't.  Skip the paper.