Ungraded vs MS66 1991 S [MOUNT RUSHMORE HALF DOLLAR PROOF] Modern Commemorative: price difference
1991 S [MOUNT RUSHMORE HALF DOLLAR PROOF] Modern Commemorative value — Ungraded $20 vs MS66 $54. MS66 sells for 2.7× Ungraded (+170%). Prices updated August 2026.
Medians of real sold listings per grade, updated August 2026 — how we compute values.
MS66 sells for 2.7× (+170%) the Ungraded price — a $34 difference per coin.
Should you get this coin graded?
Grading runs about $30 per coin all-in. On 1991 S [MOUNT RUSHMORE HALF DOLLAR PROOF] Modern Commemorative, the jump from Ungraded to MS66 is worth $34 (2.7×) — 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).