The article is a bit overly kind to Roman genius. Romans didn't deliberately produce nanoparticles. I'm not sure about the silver, but gold added to molten glass automatically disperses (dissolves) into nanoparticles; it was a problem for glassmakers hoping for gold glass who ended up with rose glass. So this is less Anythkea mechanism and more dumb luck that the Romans deliberately harnessed.
The basic glassworking is incredible, though. Romans would cast multiple shells of glass together and carve out those 3D bas reliefs.
It's technically not nanotechnology, if you simply say that anything with an active nanoscale component is nanotechnology then you can encompass pretty much everything. The cup of tea I just made is a man made process depending on nanoscale interactions, but it would be foolish to say it is nanotechnology.
The most accepted definition goes along the lines of: to be classed as nanotechnology a product has to operate in some way on the nanoscale and that operation is deliberately engineered and critical to the product's performance. In other words intent is key.
Aside from that though it is still a very impressive piece of work. I've seen similar ancient glassworks in London museums and it amazes me the colours and quality that could be made.
Some gold items found at Stonehenge were so small that they could only be made by young people, probably children. Tiny twisted pins made of gold flakes which my eyes could hardly see, let alone make. That was 2000 years before the Romans.
these are interesting, espically the Rynn's definiton based on all the marketing hype around a lot of nanotechnology, I think Tetly's probably have as much a claim as some of these products.