Plain 4: The "Plain 4" refers to the numeral "4" in the date. There are two varieties for the 1804 eagle - one with a "Plain 4" and another with a "Crosslet 4," which has a small crosslet (cross-like mark) on the bottom of the numeral "4."
1. Proof: Proof coins are specially made for collectors using polished dies and planchets, resulting in a sharp and detailed finish. Proofs were not produced for general circulation but were often created for presentation or sale to collectors.
So, an 1804 Turban Head Gold $10 Eagle described as "Plain 4 - Proof - Restrike" would imply that it has the "Plain 4" variety in the date, was struck as a proof, and is a later re-strike rather than an original issue from 1804.
Given the complex nature of numismatic terminology and the potential rarity and value associated with such coins, it's crucial to have any coin with this description
authenticated and appraised by reputable numismatists or professional grading services.
Additionally, historical documentation and provenance are essential factors in establishing the authenticity and value of coins with unique attributes.