So why are the bottles amber colored?
For starters, I knew I wanted to bottle all the Twigscent liquid fragrances in glass. Plastics are not the best vessels for fragrance. Plastics are more affordable but glass does not dissolve or breath like plastic can, so glass can help preserve a fragrance longer. Essential oils can dissolve plastic, so stay clear of plastic containers for fragrances. The applicator for the 30 ml and 15 ml is also made out of glass (glass rod - also has an old world charm about it!).
The amber color is to help prevent light deterioration of the delicate ingredients. Sunlight can deteriorate the integrity of delicate ingredients including essential oils. Think of beer bottles. Many are amber colored because of the same reason - keep out the sunlight. Many big designer fragrances are bottled in lovely clear glass. I think that they are quite beautiful, but really do nothing to protect the fragrance. When you see a clear glass stored perfume, it is usually an indicator of a) a chemical fragrance or partially chemical fragrance OR it is alcohol based or made with preservatives; b) it might be "natural" but the perfumer doesn't realize that the clear glass is allowing sunlight to ruin their fragrance; OR c) the perfumer doesn't care about the quality of their product or protecting their fragrance.
These might not be all the reasons, but some red flags when purchasing a fragrance. Keep an eye out and you'll see it happening everywhere. Twigscent fragrances will be bottled in amber glass or other safe vessels that are darkly colored.
And now you know. :)