Ungraded vs MS66 1991 S [MOUNT RUSHMORE PROOF] Modern Commemorative: price difference
1991 S [MOUNT RUSHMORE PROOF] Modern Commemorative value — Ungraded $56 vs MS66 $93. MS66 sells for 1.66× Ungraded (+66%). Prices updated August 2026.
Medians of real sold listings per grade, updated August 2026 — how we compute values.
Ungraded vs MS66
$56→$93
MS66 sells for 1.66× (+66%) the Ungraded price — a $37 difference per coin.
Should you get this coin graded?
Grading runs about $30 per coin all-in. On 1991 S [MOUNT RUSHMORE PROOF] Modern Commemorative, the jump from Ungraded to MS66 is worth $37 (1.66×) — if your copy grades at the top, that premium can cover the fee. A grade below the top one changes the math, so run your exact numbers first.
Run the grading break-even math →Values are estimates from real sales data — not appraisals or offers. Some links earn JunkPal a commission at no cost to you (disclosure).