A guide to the handling and cleaning of these blown glass wares...

First thing to know: Blown glass is actually really robust! 
Especially when chunky, like I've designed these buds to be.
I'm sure these pieces have years of everyday wear-and-tear in them for you.
To give them the best chance at long life, please remember that extreme and uneven temperatures are not their friend. 
They are able to withstand heat, as long as it's evenly distributed... one problem I've noticed with common tea light candles is that the metal tray they sit in gets very very hot at the base as the candle burns down.
So my recommendation is to use pure soy or bees wax candles, with no metal wrapper. To clean the excess wax out after use, you can give the glass an immersive bath in warm-to-hot water (not boiling though) to release the residue. 
If tea lights are your preferred choice, then just pop a small amount of water in the base before lighting, to float the candle slightly and disperse the heat more generally so you don't get a crazy hot spot of stress in the base of your vessel.

Second thing: Bumps and knocks happen! 
But if glass hits glass (or concrete or stone) with too much force, you may notice a tiny "bruise" appear on the glass at the impact point. This very small surface fracture is not a problem, just a scar that will not wipe away. Of course, big drops from tabletop level may be fatal if the floor is concrete, tile or stone! But my kids have certainly tested out my wares over the years, and they do okay in almost all accidental scenarios. Also it pays to remove jewellery when handling, as cut stones and sharp edges can scratch.

Lastly: Use a clean cotton or microfibre cloth to wipe excess oils from handling from the surface. 
I also use a gentle allergy-and-eco-friendly "universal cleaner" type spray product, but you could equally use Windex if that's what you have handy. For heavily soiled surfaces I've had streak-free success with dishwashing liquid or a capful of sugar soap (available at hardware stores) in a sink full of warm water, rinsed off with cold and polished dry.

Hope that's demystified glass care for you, but do get in touch with any lingering questions! 
And, most importantly, please enjoy using your wares on the daily <3