Sorcha: I don't recall the specifics on the "Jewel" set-up, although I have heard it discussed. Autoharps can be widly individualized, in all kinds of tunings, scales, chraomatic or diatonic. The arrangements and alignment of the chord bars can be individualized. Lots of autoharp players will have key specific, or song specific, harps. I tease these folks, when they come to a jam with ten harps.
The woods chosen and the sound-holes are specific too. Some people like a softer wood on top, or bottom, etc. My favorite harp has a mulberry body, cherry chord bars, chestnut trim, and oak rests. And, a birch top. Its a chromatic. The oak is from a cabin that A.P. Carter built. The mulberry from the Carter Fold, the cherry from Patsy Stoneman's homeplace, and the chestnut from Orthey's.
    At these "championships" like Winfield or MLAG, these custom harps are given to the winner, and the luthier will further customize them for the winner. Sometimes these unique set-ups "just catch-on," in terms of popularity. And, that's all I know about them!!!