Do spice containers need to be hermetic?
Based on my understanding of physics I would say: Opaque over airtight.

Things you don't want in a spice container are:


convection. An open container is essentially an invitation for the spices to diffuse into the whole room. Even a simple cap will already greatly reduce this effect. The amount of air that's going to be exchanged through a not so airtight cap over a hermetic seal probably pales in comparison to the amount of air that is exchanged whenever you use the spice.
sunlight. Amber glass is going to be clearly better at this than clear glass. It's unclear whether the problem is the light itself or simply the light's ability to transfer heat to the spices. I'd say the latter will probably weigh more heavily. Regardless though the amber glass will be better at both blocking light from getting to the spices and at radiating heat away from the container.
heat. Both containers being glass they'll be about equal when it comes to dealing with heat directly transferred onto the container.


Technically, if your container had very little spice in it then there might be some constellation where a the clear container could beat the amber one based in its ability to let light energy pass through it without affecting either the container or the spice.