Update on the tortoise.
Our dealer was rather enthusiastic, testing and confirming each piece is genuine. The "hero" pieces in her eyes are the neckchain and the cloak clasp. She believes the hallmark to be ca. 1840s (young Victoria head), but this is yet to be confirmed. Her valuation included retail prices on individual items and were very good. She mentioned one or two pieces might have been galapagus tortoise (also unconfirmed). All in all its a tidy and valuable collection.
If anyone here has any further info on shapes, origins, identification etc, please feel free to chime in.