Two factors affect the number of altered and forged instruments. The passage of time increases the rarity of vintage instruments and major social and technological changes have led to the operation of the largest skilled workforce in our history involved with guitar making. Simply put, there are more instruments that would be valuable enough to copy and there are more skilled people, greater availability of training, and better tools than ever before to create them.
One instrument value affected by these trends is the Gibson Lloyd Loar F-5 mandolin. The Loar-signed F-5's, made between 1922 and 1924, have experienced extreme market escalation in value over the years. In 1930, there would not have been any incentive to make a copy of one because an original was readily available at a low cost. By 1970, when an original would have cost approximately $1500, there were few forgeries around. Now there is greater incentive to copy one as its value can be approximately $30,000. Today there are far more forgeries of Loar signed F-5's than originals.
The increase in popularity of schools of luthiery and the large enrollment numbers of professional organizations for guitar makers reflect a strong interest in luthiery today. Both the Guild of American Luthiers and the Association of Stringed Instrument Artisans have over 2,000 members each. Today more people are able to work as luthiers because formal education on the art is now available.
Quality and availability of tools and equipment used in guitar making have improved and added to the increase of non-original instruments as well. Until the late 70's, decent hand tools for guitarmaking were not available -- they had to be made. Today books, schools, and tools are available. This benefits not only guitarmaking, but all forms of hand craftsmanship, improving everything from glass blowing to pottery to metalworking. Consumers are more willing and able to pay for art, and many artists who started with self-taught experience using primitive tools and little formal instruction have become professionals.
It used to be that an original finish was easily distinguished from a refinish. In the past, if the finish was smooth and professional looking, it was original. If it looked like barn paint applied with a broom, it was refinished. Few exceptions to this existed. Original instruments not only conformed to standard catalog specifications and looked typical of the makers' workmanship, but were also neat and clean. If the work was good it was original and if it was not good it was not original. This is no longer valid. Many people who refinish instruments are so skilled that they can artificially simulate the appearance of age. If the refinish is a few years old, it may be so questionable that the history of the instrument should be checked.
Now repair people modify, repair, and customize instruments. In some unfortunate cases they even produce flat-out forgeries, with extremely good workmanship -- good enough to fool most people and to cause trouble even for professionals.
Competent repair work is a different issue. Repairs are sometimes needed, but fully original instruments bring higher prices than repaired instruments. The following classes of instruments should be considered when looking at original versus non-original pieces:
1) The all-original piece: A completely unchanged example. The instrument is the same as when it left the factory. It is not repaired or customized. Even with an all-original example, however, condition affects monetary value. An instrument can be all original but very worn, or it can be all original and look like it was left under a bed and never touched. Obviously, the cleaner the instrument, the more it is worth to a collector. Fully original instruments tend to be the hardest to find because the older the instrument is, the greater the chance that over the years it has needed work or has been changed in some way.
2) Repaired Instruments: An instrument that underwent a needed change. These may still be very fine instruments. For example, a 20-year-old Martin guitar may need a neck set. A well-done repair can be virtually invisible. An instrument that has been professionally refretted is preferable to one that is unplayable because of severely worn frets. However, an instrument with playable original frets is, of course, even more desirable.
In the case of warping, cracks, breaks, or extreme wear, repair work should usually be done. The best repair returns the instrument as closely as possible to the original specifications and is virtually undetectable. Repair quality has improved greatly over the years for the aforementioned reasons, but there are many older instruments suffering from bad repair work. Much of the work being done in repair shops today is undoing previous repairs. Often these repairs are the most difficult, expensive, and aggravating. Repairing an unrepaired crack is much easier and usually ends with a better result than trying to restore a poorly repaired crack.
Lacquer checking or cosmetic damage not affecting the playability or structural stability of the instrument should be left alone. Frequently, a touched up or refinished instrument is worth less than an original one with some blemishes. Careful inspection of an instrument should be made as a repair is not always obvious if the repairman was highly skilled.
3) Customized Instruments: Instruments altered in any way not necessary for playability. Customizing includes modifying an instrument to look like another or to be unique. For example, a Martin D-28 could be made to look like a Martin D-45 by stripping the finish, inlaying abalone, and refinishing. On electric instruments, pick-up, tailpiece, and finish changes are common. Stage or studio instruments are often changed to make them more eye-catching or to affect their sound under special circumstances. To a collector these kinds of changes are damaging regardless of the quality of the job. It may make the instrument more appealing for stage or utility use, but not as a collectible investment.
Fender guitars are common targets for modification because they are built much like erector sets: everything on the guitars comes apart and many of the parts are interchangeable. Be careful that things match, because even if the parts are Fender made, it may be assembled from four or five different Fenders.
4) Forgeries: Instruments designed to be impostors. These are built from the beginning as such. Because of the effort involved in making an entire instrument, these are generally replicas of high-priced items. Fakes of instruments such as the Gibson L-6S are uncommon since originals sell for under $500. Generally, forgeries are copies of expensive Martins or popular Fender and Gibson electric guitars. Forgeries of solid body electrics are easier to produce than forgeries of acoustics.
Fender bodies, necks, and many other parts are easily copied and duplicates of these parts can be bought from a variety of companies such as Warmouth and Boogie. Solid body electric instruments like Flying V's and Explorers, which can be valued at close to $50,000 for an original, are unchallenging for a skilled luthier to forge, as these guitars are made with no body binding or fancy inlay.
Ultimately, how can the originality of an instrument be determined? Tiny details and research will expose a forgery or alteration. First, does the instrument conform to the catalog specifications of the model for the year it was made? If it does, it is more likely to be original, but this is not a guarantee. If the instrument does not conform, it is suspicious. However, exceptions do exist. The instrument may be a custom order piece or even a prototype, although chances of this are very rare. Someone who knows the catalog specifications of the instrument should check. Use of a reference book like Guitar Identification by A. R. Duchossoir or Gruhn's Guide to Vintage Guitars, which lists specification changes by time period, will also help.
If an instrument is purchased from a reputable dealer, they should be willing to write a certificate of originality. The reputation of the dealer is of paramount importance when buying instruments. Good dealers will ship on approval and put in writing what they are selling.
Furthermore, if the instrument conforms to the catalog specifications for that model and production year, it should conform to the workmanship of that maker. This part is a lot like handwriting analysis. A luthier's workmanship will be just about as distinctive as his handwriting. For instance, one luthier's neck joint is done differently from another's, and different tooling, jigs, and patterns are often used. Major manufacturers do not do these things the same way. If you believe a guitar to be a Martin, it should show Martin craftsmanship on all details of workmanship and design.
Hand makers producing a forgery will deviate from these specifications in some details of workmanship or components. It is not because they are not skilled, but because they do not have the patterns and tools that the original manufacturer used to mass produce the instrument. Manufacturers rarely changed these tiny details as deviation would have required repurchase of large machinery and bulk supplies. This is an effective way to identify an all-original factory instrument in which color or fingerboard inlay may not be typical. If the small details are correct, the instrument is probably original. There is no substitute for a keen eye and experience in evaluating instruments. If you are not an expert, it pays to rely on reputable dealers.