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In particular, while the ban remains near wholesale, the trade in portrait miniatures will be permitted within the state lines, under rules outlined by the Department of Environmental Conservation (DEC).

It is a last-minute amendment to the bill - one that permits the sale of items at least 100 years old that contain less than 20% ivory - which has provided the 'wriggle room'.

The guidance around the 20% rule issued by the DEC on December 4 allows for the possibility that canes with ivory handles and boxes and caddies that use ivory veneers around a timber carcass can be sold.

Under the heading How do I determine whether ivory… comprises less than 20% of an antique?, the notes say "a reasonable estimate of volume, weight or surface area is acceptable".

Importantly, the document (available via the DEC website) includes a specific clause permitting the sale of portrait miniatures on the grounds that the veneer of ivory used as a support is "no thicker than a piece of paper".

In addition, the guidance states: "The percentage of ivory by volume used in the portrait miniature will be presumed less than 20%."

Rhinoceros horn and mammoth ivory are subject to the same rules that passed into law in August, despite opposition from Sotheby's, Christie's and trade associations including the Art and Antiques Dealers League of America and the Appraisers Association of America. 

US Federal laws introduced in February, covering the entire United States, already tightly restrict ivory imports and interstate sales.

In essence, these nationwide regulations ban the commercial import of African ivory of any age, while domestic and export trade will be limited to antiques defined as objects more than 100 years old.