Alexander III, The Great - Museum Gallery

Alexander the Great (336-323 B.C.) LIFETIME Issue. Ob: head of young Hercules r., clad in lion's skin; Rx. Zeus enthroned l., feet on stool, holding eagle and sceptre, the Greek word 'ALEXANDER' behind; beneath throne there's a pellet and an 'M' monogram; field under the eagle has an incomplete symbol, which may represent a bee. Weight is 17.2 gm & it's 24+mm in diameter.

Alexander the Great types were minted over a longer period of time than just during his lifetime. Many collectors prefer owning a known 'lifetime' issue. While having confidence that a particular coin is 100% lifetime is never assured there are certain characteristics that can bring it very close to a certainty:

1) Look for the parallel leg issues. Although I believe there are a handful of crossed leg issues struck just at the end of his lifetime,
the vast majority of crossed leg examples will be posthumous.

2) Look for issues without Basillios (Greek for King) in the inscription. Alexander
adopted that title late in his life, so there
are many lifetime issues with that inscription type, but the majority
are not. But keep in mind there are non Basillios inscription types that are latter, but most of those will be crossed leg types already eliminated.

3) Look for issues on small thick flans. Nearly all lifetime issues were on such flans, and virtually all broad flan types are later to much later.

4) Look for issues with fairly simple engraving on the lion's skin mane. Most of the ones with more elaborate mane's are later.

5) Tetradrachms having appreciably less mass than the Attic standard of 17.2 grams are much more likely to be posthumous issues.

So if you find a small thick flan, with a simple lion's mane, with parallel legs and without the Basillios inscription, it is most likely going to be a lifetime issue.

Articles to VIEW and DOWNLOAD:
An excellent article that features a story about the discovery of the only known living portrait coin that shows the image of lifetime portrait of Alexander the Great (not Herakles)is linked below. It's a MUST read!
Ptolemy's Egypt & Alexander's Portrait - Holt: /library/Ptolemy's%20Egypt%20&%20Alexander's%20Portrait%20-%20Holt.pdf
Here's a very informative & illustrated paper on "The Spread of Coins in the Hellenistic World" by A. Meadows: /library/Coins%20in%20the%20Hellenistic%20World_A%20Meadows.pdf
Hellenistic Coin Portraiture - Sheedy: /library/Hellenistic%20Coin%20Portraiture%20-%20Sheedy.pdf