Gene,
An example or two of “Rosace” engraving:

[Linked Image from jpgbox.com]

[Linked Image from jpgbox.com]

This engraving style was called rosace in the Paul Bruchet era of Darne shotgun production (third gun, last photo) and this pattern was designed by an engraver by the name of Guy Ripamonti. It was not used on Darne guns prior to about 1980. There was a rosace pattern available prior to Guys involvement, but, it is nowhere up to his level of skill. It was the default engraving pattern on R15 and V21 guns of the Bruchet era, although you could specify any engraving you wanted, and could pay for. I have a catalog of guns produced by Ripamonti, and that pattern was not used on guns in that catalog. Perhaps you could order it, but, I have never seen a gun other than a Bruchet produced Darne so engraved. Doesn’t mean it didn’t happen, but, it didn’t happen often, for sure, and I’ve been looking for about 40 years.

I can’t say if this is the same, stylistically, as what your catalog refers to, but, it is an example, that is widely known. More than one house engraver could pull that pattern off on a Darne (Ariel Recrux, for sure, perhaps others) but, Guy had a touch that brought it to life.

Best,
Ted