A pretty interesting story I found:
Blossa Glogg + BVD Bottle Design : For the 8th year in a row, BVD presents the annual Blossa Glögg for 2010. This year's flavour is saffron and the bottle's colour is gold. Gold is an iconic colour that reflects the festive nature of Christmas as well as the taste: saffron with its golden colour is one of the most exclusive of all the spices. The Roman X is used as a symbol for the number 10, but is also a hint at the English X-mas.
"A vintage mulled wine for a new decade is a reason to celebrate. We wanted to create a really festive bottle, and the Roman X felt like a worthy symbol the decade's first annual edition". Says Susanna Nygren Barrett, Creative Director at BVD.
Blossa Annual Edition has become a success story which creates a demand around the mulled wine season every year thanks to a new flavour and design. Blossa Annual Edition exceeds sales from year to year, and continues to sell out within a few weeks, increasing customer expectations. The design plays an important role to create excitement and engagement around
Below, have a look at the bottle designs from years prior: