Dirk style kilt pin - antique or not?

[Tobus]

My wife bought this at an estate auction yesterday. They were calling it a Victorian brooch, and apparently she was the only one at the auction who knew it was a kilt pin. She had the good sense to keep that info to herself until she had won the bid, and only paid $37.50 for it. The estate was of an elderly couple, and I didn't get the sense that there were any other kilt-related items in the estate. So they may have bought it long ago thinking it was just a brooch or pin, not knowing it was specific to kilts or Scotland or anything like that. This would suggest (to me, anyway) that it isn't a modern knock-off or replica that seems to be commonly sold to kilt-wearers. But I could be wrong.

Those of you who may be knowledgeable in such things, help a brother out! Does this appear to be a genuine antique kilt pin, or a modern replica? I couldn't find any hallmarks on it during my brief inspection last night, but I may not know where to look. The only marks I see on it are the words "HOLD-ON" stamped in the brass keeper on the pin shaft.

It appears to have quite a selection of stones. Would that be cairngorm at the top of the dirk and at the little utensils? I assume it's agate in the main body. But I'm not very educated on stones or jewels. The detail work in the silver appears to be well-done, by hand, and not a cheap hack job, but again, I'm not well versed in such things. Give me your impressions of the quality, if you think it might be pertinent to determining its authenticity.

*edit: for some reason, my attachments won't show up. I'm posting them from Photobucket...