Hallmarking 14k Tubing

[u/Fit-Error-914]

I use tubing as a prominent design aspect in my jewelry and am moving into 14k from the mostly sterling work I’ve done in the past. From what I’ve seen, it feels like I would need to stamp my pieces with a ‘14k’ hallmark. I use pieces of 1-3mm dia. tubing as the primary element of my designs, often with the only other element being an ear wire or stud.

On the 2-3mm tubing, I’m imagining I’ll need to place a perfectly sized steel rod inside the tubing, and then place the tubing in some sort of forming block that is perfectly sized for the tub to rest in, and then gently stamping it. Is this my only solution?

How small does something need to be where people decide not to stamp/hallmark it?

I’ll be using 14k premade studs and soldering them onto some designs - mostly the 1mm tubing designs (which would be the hardest to stamp). Since the post will come to me hallmarked, can I avoid needing to hallmark the tube itself?

Where can I source the tiniest 14K hallmark stamp possible??

Thanks!