There are several ways to determine if a dog tag is real. While these steps will work for just about any dog tag from any military in the world at any given time in history, the specifics apply to present-day American dog tags. If you want to determine the legitimacy of dog tags from other nationalities, you will need to find out the answers to the parameters outlined below before using the steps as a guide to analysis. With proper historical checking, nearly any dog tag can be verified as real or fake.
Check the order of the information on the dog tag. If your dog tag is an authentic U.S. military dog tag, the information should be in the following order: last name, first name, middle initial, Social Security number, blood type, religion.
Check the necklace type if possible. If you have the complete set of dog tags and they were made after 1943, one tag will be on a necklace 25 inches in length and the second will be on a necklace extension not more than 2 1/2 inches below the first necklace. If the necklace is older than 1942, it may be nylon, rayon or cotton. After 1943, the beaded necklace commonly seen today became the norm. You can not only check the necklace type against the dates, but also check to see if the necklace type fits any of the requirements for military dog tags.
Determine if the metal type is historically appropriate. While dog tags were initially made of nickel, during World War II the Army opted for a stainless steel dog tag over brass or nickel, which were on the critical supply list. Dog tags made after 1945 are nearly always made of stainless steel.
Check the serial number. If your dog tag has a serial number and it dates from after 1969, it is probably fake. The Army switched to Social Security numbers after 1969. From 1967 to 1969 a dog tag might have had a serial number, a Social Security number or both.
If you just want to make sure that your dog tags are authentic in terms of lettering, style and materials, rather than determining what type of historical role they played, take them to an Army surplus store and ask if they are the "real thing." Since you can get the real thing made at these stores, it will be easy to compare and determine whether your dog tags are correctly designed.