Vintage is vintage which means an item 20 years old or older - not sure when it turns into an antique - anyway; manufacturing processes, packaging, raw materials change with time which is one of the best ways to tell time period.
Swarovski crystal is a good example. The packaging on their vintage beads tells whether or not their beads, crystals, rhinestones are vintage.
Packaging is not so much the tell for Czech glass beads, but it has more to do with color saturation and consistency in bead size. The way Czech beads are strung also tell time period; for example some of the beads pictured are strung in a way that hasn't been practiced in decades.
Also when you have the beads in front of you you can clearly see the inconsistencies in color saturation and bead size. Some are just a tad bit bigger than the others coming from the same bead lot (production).
Many of the Czech beads were obviously made for sewing, bead embroidery and embellishing. They have flat bottoms and dome shaped faceted tops - looks like the precursor to flat back crystals; and they're quite small too 3x2mm, 3mm some with 2 holes (not pictured, but available).
And the red and white striped ones (pictured) with a domed pebbled top must have been a nightmare to produce!
Even though it can be more challenging to authenticate a single bead or loose beads - it's easier if in original packaging, multi-strand hank or string - know that vintage beads can be authenticated in the sense that a bead seller in the know' (meaning that they will let you know if they have knowledge in this area) may be able to tell from the look and feel.
If purchasing from an estate sale or open market try to get some history about the seller or estate. Even if it's already a piece of jewelry depending on the condition you can always rework into a new piece.
Remember we're talking beads, and although vintage beads can have high resale value they're not fine, estate jewelry.
Many years ago there was a vintage only bead seller online and their website helped me identify and gain knowledge of the beads I have but the website seems to no longer be available.
I hope you find this information useful.
Oops almost forgot this important note.
Czech glass bead manufacturers have something they call Job Lots; I'm note sure why they make them but they are like one-time production bead runs and often in odd-sizes, odd-shapes and odd-types. Because of this they can be confused for vintage beads.