Because of its excellent quality, this coin is a rare survivor of this date, which appears to be more frequently encountered in lower grades than other dates of this era. A possible explanation is given for this in Breens Encyclopedia of Colonial and U.S. Proof Coins, published in 1977. Therein a letter is reprinted that blames a contemporary Mint employee for defacing many Proof gold coins, and telling lies to a customer of the Mint at that time. While unconfirmed, the letter is an interesting read and could very well be true.

Like many dates, the business strike mintage of the 1866 quarter eagle was very low as well, and the overall supply is low for both business strikes and Proofs. Quarter eagles, among the smallest of the 19th century gold denominations is a long and difficult set to complete, in both Proof and business strike format. Yet, the inclusion in a collection or portfolio of gold coins of a few of these pieces makes for an attractive and varied display and a safe investment, as these rare gold coins have proven to hold their value for a long period of time, steadily rising in price.

Dark orange-peel surfaces with heavy frost on the devices and reflective fields make for a very attractive coin. The present specimen is virtually unimpaired on both sides, with only a few minor hairlines keeping it out of a gem holder. The eye-appeal is excellent, with a, as expected, strong strike that brings out all the detail. The date is large and prominent, with the numeral 1 showing no signs of repunching, a characteristic for the Proof die. The business strikes show minor repunching on that digit, and on some lower graded examples it might be needed as an identification mark. On this coin, there is no reason to dispute its true status as a Proof, and this check remains totally unnecessary on all accounts. This coin has been stickered by CAC.