The United States' "Persian rug" stamps

In the nineteenth century, "revenue stamps" were purchased and used to pay taxes on a variety of items and transactions - mortgages, deeds, cigarettes, wine, oleomargarine, life insurance, playing cards, etc.

Concerned about fraudulent cleaning and reuse of such stamps, the Bureau of Internal Revenue in 1871 issued a new set of stamps (the "Second Issue') with elaborately detailed designs and colors and a special paper which incorporated silk fibers.   A most interesting article (pdf) in the American Philatelist offers more details:

The original tax schedule included several open-ended rates, and stamps were created that were, in principle at least, adequate to pay them. For example, a deed for real estate whose value exceeded $20,000 was taxed in multiples of $20 (at $20 for the first $20,000, plus an additional $20 for every additional $10,000 or fractional part thereof ), to be paid by $20 Conveyance stamps. In practice, though, this proved unwieldy. For a property with a $200,000 value, a total of 19 $20 stamps would be required; and for $500,000, 49 stamps.

When the First Issues were replaced by the Second Issues in September and October 1871, the $200 denomination (Scott R132) was retained and a $500 (Scott R133) added, to further facilitate payment of large taxes, on deeds or mortgages for amounts exceeding $500,000, or estates exceeding $1 million. To foil counterfeiters they were printed by a complicated tricolored process, the world’s only engraved tricolored stamps, considered by many as the most beautiful stamps ever printed. The abrupt repeal of the documentary stamp taxes effective October 1, 1872, ensured that these stamps would be as rare as they are beautiful: just 446 $200 stamps were sold, and 210 of the $500.

The article at the link has several awesome photos of multiples of these stamps being used on documents (deed for a silver mine, for example).

Photos for this post are of nonperforated die proof singles for these issues; I found them in The Stamp Collecting Forum.