PCGS Nos: 9378

Mintage:
Circulation strikes: net 1,314,709 (2,314,709 struck less 1,000,000 melted)
Proofs: 1 reported

Designer: Gutzon Borglum

Diameter: ±30 millimeters

Metal content:
Silver - 90%
Copper - 10%

Weight: ±193 grains (±12.5 grams)

Edge: Reeded

Mintmark: None (for Philadelphia)

Images courtesy of Heritage Numismatic Auctions

Notes:
The 1925 Stone Mountain Commemorative Half Dollar is very common and is often found in nice condition.  The most frequently seen Uncirculated grade is MS-64, but even MS-65 examples are common.  The finest Uncirculated examples graded by PCGS are 6 MS-68's.

Walter Breen reported one matte Proof, whereabouts unknown.

A rare, doubled die obverse exists...check the date, where the doubling is most likely to be seen.

Some examples were counterstamped with a state abbreviation and a number.  These are scarce and command a significant premium, which also means you must watch out for fake counterstamps.

Significant examples:
PCGS MS-68.  Heritage "NY Invitational" 07/2004:7615, $24,725.00

Sources and/or recommended reading:
"The PCGS Population Report, July 2004" by The Professional Coin Grading Service

"Walter Breen's Complete Encyclopedia Of U.S. And Colonial Coins" by Walter Breen

"The Encyclopedia of Silver and Gold Coins:1892-1989" by Anthony Swiatek and Walter Breen

"A Basic Guide to U.S. Commemorative Coins" by Michael Hodder and Q. David Bowers

"Commemorative Coins of the US: A Complete Encyclopedia by Q. David Bowers

"The Official Guide to U.S. Commemorative Coins" by David Ganz 

"Investing, Collecting, and Trading in Certified Commemorative Coins" by Harry Laibstain