When you hear "sodium" it's usually in reference to your diet and how it - along with all the other yummy stuff in junk food - is bad for you and you should cut back. And to most people that's what sodium is. Just another label boogeyman. But when it's not bound up chemically with dancing partner chlorine (or practically anything else) it is a gleaming metal that looks identical to the backing of a mirror. Getting it free of all the other elements that would readily pair up with it to wipe away that luster is a benchmark laboratory challenge for the budding chemist for it requires absolute precision in engineering an environment that is either like outer space or infused with a noble gas, typically argon - the only thing it refuses to pair up with. 

Keeping it shiny like this means that that pristine atmosphere has to be carried wherever it goes. If the glass should break you'll watch in horror as in less than five seconds your precious bit of sodium metal turns the color of week-old pizza. Worry ye not one bit though. This otherwise fragile glass ampule is safely suspended in the middle of this crystal clear block of Lucite resin. Barring some very determined effort it will stay probably remain flawless until the day the sun swallows the earth!