What this coin looks like (obverse, reverse, mint mark location, special features, etc.):
One major variety of the 1843 O Liberty Head $2.50 Gold Quarter Eagle features a Small Date and Crosslet "4" in the 1843 date. The small date has much smaller numbers and always features a crosslet on the right side of the number "4". The difference between the 1843 O Small Date vs Large Date (Crosslet 4 vs Plain 4) gold quarter eagle is depicted below in the example comparison image:
Coin valuation chart: Typical coin prices, values and worth per grade or condition - in USD