The following chips are group by age as I believe them to be. I welcome any corrections.

The first group is distinguished by the fact that the inlays appear to be full color lithographs. Unfortunately that were not well made. Chips in this group have, for the most part, lifting inlays. It is my contention that the reason for the lifting inlays is that the company (USPC???) backed the celluloid inlay with paper. Over the years the celluloid dried out and cupped. Some chips in this group have inlays where the ink has run. This was due to water getting under the inlay.

In the second group USPC got it right. They backed the celluloid inlay with a thinner celluloid inlay (on which the litho was printed). This celluloid sandwich eliminated the stress as happened in the older inlays. These inlays remained flat and tight. Unfortunately USPC decided to cut back on the quality of the lithograph. Inlays in this time period (1910s to 1940s) are, for the most part, two-color lithos.

The Burt Company took over in the mid 1940s. Rather than use celluloid (cellulose nitrate), the company used plastic. Plastic was cheaper and safer. Celluloid was quite flamable. Additionally celluloid was imported from Italy and quite expensive. The only negative is that Burt chips don't have that certain patina that the USPC chips gained over the years. Think of the difference on a wooden floor between a clear oil finish and a clear acrylic finish. The oil will yellow or darken the floor whereas an acrylic finish will not change the original color.

In the third group, Burt cuts down on the thickness of the plastic seal. The process is cheaper but the inlay will wear through sooner.

The fourth group is the only group I would not consider a crest and seal. The seal is nonexistent. If not for the lack of a clear protective film over the inlay, I would have classified these chips as crest and seals. They would be considered just plain molds with inlays.