the more I look at this piece, the more I think it is not Davidson. According to the Stewart book, the part of the piece that is the 'registered design' is the shell motif on the side of the canoe, not the canoe itself.
I have all 6 of the Davidson WAR OF THE ROSES canoe shapes. There is a tri-corner, a quad-corner, a small, medium and large canoe, and a canoe with twig handles.
On all but the multi-corner canoes, each canoe has 7 shell designs on each side. on the 3 & 4-corner pieces, there are 6 shells from point to point. The piece in question has 5 shells on each side.
On the underside of each piece, there is a sunburst ray pattern in the center, and then additional ones that point towards each tip. (standard canoe has 3 rayed designs). On the tri-corner, there is 3 pointing out and one center, and on the quad-corner, there are 4 pointing out and one center.
On each center of all shapes, the sunburst pattern has 36 points for the center design and 21 points for the ones that point towards the ends. On the new piece, the center sunburst has 32 points, and 19 points on the ones that point towards the ends.
On all 6 originals, there is an Rd. number, embossed on the inside base of each dish. There is none on the new piece.
I considered the non-opal to be the least significant detail, as I have had Davidson pieces (in the same shape) in both primrose pearline and without that effect.
I believe this piece is old, but now believe it is just a reproduction of the shell pattern with a similar shape. Ferrer from Germany copied three different shapes of the LORDS AND LADIES pattern made by Davidson, and those were made about 1907. That would be the first 'suspect' possibility on my list, but it could also have been made by other companies. It was found in Sweden, but that does not mean it was made there. As it is a pressed dish, it will be interesting to find out if anyone has ever come across another, or in another color. Moulds weren't made to make just one piece, so there has to be more of them out there.