There is a myth that says that glass stops ultraviolet radiation completely. I personally heard it for the first time in elementary school, during physics lesson, and I took it for granted for a long time, more precisely, until some technical experiences proved to me the opposite. And here's what it omitted, the Physics Manual (for children), to state:
The ultraviolet range is in fact a spectrum of frequencies. They are grouped into four subspaces, UVA, UVB, UVC and UVD. Since UVD (less than 100nm wavelength) can only propagate in the vacuum, of course we can not care. About the rest, in Figure 1:
Figure 1: Ultraviolet radiation spectrum
As you can see, UVC radiation is not of interest, but UVB and UVA is of interest for uus, because they can reach the ground (and even get there). As such, for a minimal influence on colloidal silver, the vials in which it is stored should absorb these ranges of radiation. This need has long been studied in the food industry, and is still due to the fact that there are many liquid food products that are likely to be destroyed / degraded by ultraviolet radiation. As wine, beer, oil (especially olive, hemp) producers have noticed this need, we have also made inquiries on bottles made from various assortments (and implicitly colors) of glass.
Thus, according to the report by Skouroumounis and collaborators, in 2006, the absorption graphs for different glass assortments resulted as in Figure 2:
Figure 2: Absorption of light for various glass assortments
What does this mean? We can see that the best bottles are made of brown glass and antique green (we can also include glass bottles, which are usually a green variety), because they absorb very well both the UVA and UVB range of ultraviolet.
Surprisingly (but not so surprisingly), cobalt blue absorbs very little of the UVA field, virtually as little as a colorless bottle!
However, due to the fascination that this color produces, especially in the case of shades, buyers can easily be tempted to buy it regardless of the product packed in it. We would say it is not a very good idea, especially in the case of colloidal silver. Of course, if we permanently protect the product in another extra box, it would help, but daylight, even in a normal room, or on a store shelf, some products will degrade if they are kept in such a bottle. Keeping in an opaque cabinet, however, will help in the stability of the product, but to the final customer, such a container can not be easily stored in ideal conditions.
Let's make this cler: keeping drinking water in such a bottle is beneficial, it can even help heal some diseases (also true for other glass colors: purple, red, yellow, green, blue, etc.). For example, keeping water in blue containers is not recommended for people suffering from constipation, asthenia, lack of vitality, depression, rheumatic diseases, cold, being recommended other colors, on a case-by-case basis. These details are related to a traditional medical branch, called chromotherapy, which we can not address here.
Ultraviolet radiation also affects other types of nanoparticles, such as gold, copper, platinum, etc. However, the fastest destructive effect is on silver. Of course, as the size of the nanoparticle increases (as in the case of silver-colored silver), this action is reduced, and the vials can be stored for years (even though not exposed directly to sunlight) in colorless vial.
OBS! If you perform ultraviolet radiation measurements with dedicated devices, it's good to keep in mind the range of UV rays that have been calibrated. At the same time, it is good to know that the type of glass is very important, but especially its treatment, which, in the case of modern insulating glass, can be and is easily achieved. But this is a whole different situation.