Tooled coins are coins that have suffered from modern re-engraving in a misguided effort to "improve" them. Tooled coins should be avoided. A untooled ancient coin, no matter how poor the condition, is preferable to a tooled (spoiled) coin. Tooled coins may be recognized by the following:
1. Unnaturally flat fields. Un-tooled coins often have a slightly convex obverse and slightly concave reverse.
2. Uniform smooth black or brown surfaces. Most often the original patina has been removed and the surface of a tooled coin is darkened bare metal or some other artificial patina.
3. The details are often incised, rather than in relief. For example, the details of the hair, a laurel wreath or drapery on a tooled coin often consist of simple lines cut into the original worn surface. These details may look original at a glance but the difference between incised and relief details is often easily detected with a careful examination.
4. The style is often a crude caricature of the style of untouched coins. Drapery in particular rarely captures the realistic three-dimensional flowing quality of the original die engraving.
5. The style of lettering may be different from the original. Tooled lettering may rise more vertically from the field of the coin than on untooled coins. Tooled lettering is often uniformly wide and the top surfaces of letters are flatter than normal.
If you suspect a coin has been tooled, you should compare it with un-tooled coins of the same type.
This coin, nicknamed Mr. Tooly, is the most infamous horribly tooled coin on planet earth!
See other examples of tooled coins in the fake coin reports: https://www.forumancientcoins.com/fakes/thumbnails.php?album=23
MacDonald, David. An Introduction to the History and Coinage of the Kingdom of Bosporus. Lancaster, PA: Classical Numismatic Group, 2005.
The use of tools on blown glass.