What makes an autograph valuable?

If a particular autograph is uncommonly encountered on the market it will be worth more.

If an autograph is common but currently unavailable on the market that it will be "rare" at the moment, and thus more valuable; therefore hoarding makes an autograph appear rare. But beware, if new autographs are discovered or released the price will drop as a result.

Condition

Condition of the autograph is very important.  Other collectables such as coins have much more stringent grading systems, but grading for autographs is still a bit nebulous.  In general, the grading system goes as follows:

Poor..........................heavily damaged specimen, barely recognizable as authentic
Fair...........................severely damaged autograph
Good.........................flaws detract from the autograph, but acceptable
Very good.................below average, but still a nice specimen.  May have serious folds, folds through the signature
Fine...........................average specimen
Very Fine...................above average specimen.
Excellent....................free of serious detracting defects.
Mint...........................flawless, as if it were brand new
Superb.......................flawless,  and also of historical importance.  Therefore, "superb" indicates more than just condition.

For some autographs, a grade or two in condition means an enormous jump in price.  Mint and superb items are always in high demand for scarce autographs.

Allowance is usually made for age--for instance, a document from the 1700's may have some yellowing or minor foxing and still be considered "excellent." Damage to an autograph in any form will lower the price--this includes stains, tape, removal of inscriptions, staples, pinholes, etc.

Demand

Although some autographs are plentiful they are expensive because of high demand because of extreme admiration for a celebrity.  For example, John Lennon signed an enormous number of autographs in his lifetime but each autograph is now valuable because of such high demand.

Association

An "association piece" is an autograph linking two different celebrities.  A letter from George Washington to John Hancock is an example, as is a letter from Gerald Ford mentioning George Bush.  It is easy to see why these autographs are in higher demand and command higher prices.

Date signed

This is important especially with significant dates.  A document signed by John Hancock on July 4th, 1776, would command a stellar price, while an identical one signed on December 5th, 1768 would not be quite as valuable!

Complete set

In general, a complete set of autographs is worth more than the individual components.  Expect to pay more for a set of photographs signed by each of the twelve moonwalkers than the added value of each of the photos.  You are actually paying in this case for the trouble of assembling the set.

Content

When buying letters, content greatly affects price.  A letter from Albert Einstein that says "please come by tomorrow" might bring $1000.  If the letter said "please come by tomorrow; I need help with the final touches on my Theory of Relativity," it could bring $10,000 or more.

Context

Photos showing historical context are often more valuable than ordinary portraits.  A still from "Wonderful Life" signed by Jimmy Stewart will bring much more than a simple face shot.  A picture of a president taking the oath of office is more interesting than a photo of him in his study.

Size

In general, larger items cost more than smaller items.  An index card signature costs more than a plain cut.  An 8x10 photo is more expensive than a 5x7 photo.

Multiple signatures

Generally an item signed by several celebrities is worth more than the sum of the individual signatures.  This is especially true in the case where an item has been signed by members of a particular group, as opposed to multiple signatures without a coherent theme.  Photographs signed by multiple astronauts or presidents are popular examples.

Conversely, if the signatures are not related the item may be lowered in value by the addition of other signatures.  A baseball signed by Babe Ruth alone will typically sell for about $3000.  However, if there are other signatures of minor players or unknowns on the same ball, $1000 might be a more realistic price.

Inscription

Inscription refers to a signature dedicated to a particular person, e.g. "To George with best wishes."  For modern "pop culture" items, inscription reduces the value of a signed piece by at least 20% and in many cases can make the item unsaleable. However, for historical celebrities the additional writing of an inscription is quite desirable as it aids in authentication of an autograph (see "Amount of Writing" below). Therefore, for vintage autographs an inscription may actually increase the value.

Amount of Writing

Generally, for persons of historic interest, the more handwriting the better.  A letter written entirely in the signer's hand is more valuable than a typed letter with just a signature.  A short handwritten postscript may double the price of a typed letter.  Having more writing aids in authentication and is thus more desirable.

Display Potential

Many collectors like to show off their collections.  Because of this, items that are easily framed and displayed may command higher prices.  As a result, a one-page letter will sometimes sell for more than a two-page letter because the two-page letter is harder to frame.  Signed sports equipment (baseballs, footballs, hockey pucks) are also sold as display items.  There is a whole subculture of "single signed" baseballs that has artificially raised prices on such items.
 
 

Some dealers attempt to capitalize on the above factors by stretching the facts. In fact, some are downright masters of deception.  Here are a few examples:

Questionable Date

Item #535.  John Kennedy.  Signed card, dated in his hand "Nov. 22, 1958."  (This is five years to the date of his death, important as such.)  Minimum bid $3000.

Insignificant rarity

Item #234.  Milton Berle.  Signed card.  Autographic material from this comedian is very, very rare.  Minimum bid $200.

Stretched context

Item #154.  Harry S. Truman.  Signed dollar bill. (1934 Silver Certificate) Truman was known for his famous phrase "The Buck Stops Here."  Well, here is the buck!  Very good condition.  Minimum bid $1500.

Problems with condition

Item #12.  James Fenimore Cooper.  ALS.  1830, no place.  A fine letter to a close friend regarding family matters.  An ink spill occurred while Cooper was writing this letter, and Cooper left a partial fingerprint in the left margin.  A rare opportunity to own Cooper's fingerprint.  Minimum bid $1500.

"Otherwise"

Item #90.  Neil A. Armstrong.  SP.  A stunning official NASA lithograph of the first man on the moon.  1 1/2 inch tear at top left of the lithograph, otherwise in mint condition.  Minimum bid $400.