Toning (aka tarnish outside of the numismatic world) can have a strongly negative or positive impact on a coin’s value. Unusual and particularly beautiful toning patterns can nudge a coin’s grade upward and dramatically enhance its desirability. Conversely, unattractive (or unnatural) toning can seriously limit a coin’s grade, marketability and value. This article will briefly discuss the good and the bad in the world of numismatic toning.
Over time, if stored in certain types of holders and packaging, coins can acquire dramatic rainbow toning. In particular, silver coins stored in sulfur-infused albums and bags can exhibit wild and exquisite toning patterns. Despite dealers’ best attempts to artificially accelerate the process, this kind of attractive toning takes years if not decades to develop.
If a common coin displays particularly gorgeous toning, it can sell for many multiple of what it normally would as “just a coin.” A common MS 65 Morgan dollar, for instance, sells for around $150-$200. The most spectacularly toned examples, meanwhile, can easily sell for $500-$2500. At a certain point, the coin’s standard market value becomes meaningless relative to the value of the toning.
On the flip side, unattractive toning can limit a coin’s grade and/or hamper its market value. To illustrate what might be construed as ugly toning, example would include uneven, splotchy, black/grey and spotty color. Even coats and concentric rings are good, but random streaks and blobs of toning are definitely frowned upon. For silver coins, the color brown is often deemed to be negative but it can be quite pleasant on gold.
Generally speaking it’s difficult for an unattractively toned coin to grade above MS 65. Unless the surfaces are immaculate and there is ample booming luster visible underneath the toning, coins with negative toning cannot qualify for MS 66 or above. For unattractive toned proof coins, the surfaces must be perfect and ultra-reflective to have any hope of grading Proof 66 or above.
Along the same lines, in some series, spectacular toning is to be expected for high-grade specimens. Classic United States commemoratives typically come with very clean surfaces and decent luster, so it’s not difficult for them to reach the MS 65 to MS 66 level. Often the only difference between a “commem” in MS 66 versus MS 68 is how colorful the toning is. For this reason, the majority of the classic United States commems in MS 68 holders displays beautiful color.