The 3-cent value of the First Bureau Issues is an orphan. That is, it paid no single rate by itself so it could be used only to pay a multiple rate—for example, as triple third-class rate (three x 1-cent)—or as additional postage, such as with a 2-cent to pay the five-cent Universal Postal Union rate to another country.
A holdover from the prior issue, the 3-cent value was probably included in this issue as a contingency to cover the increase in first-class postage from two cents to three cents. Printed in an attractive shade of purple, collectors are glad it was included in the issue.
The 2-cent values are the only stamps of the issue that have different triangles in their design, so the only way to distinguish the first printings from the second printings of the other values is by checking for the watermark. A stamp from the first printing has no watermark. There was no color change in this value to require a third printing.
The 3-cent stamp can be found in many shades. A crisp color on white paper is an exciting find!