What about filling the jar/vase with a tinted candle gel, and having it burning? Not a traditional candle, but transparent enough to make it interesting.

http://shop.candlesandsupplies.com/candles/category.asp?catalog_name=Candles&category_name=Ca ndle+Gel&Page=1
http://images.google.com/imgres?imgurl=http://www.csc.gov.sg/html/Newsletter/jan2006/gel_candle.jpg&imgrefurl=http://www.csc.gov.sg/html/Newsletter/jan2006/c4.html&h=329&w=350&sz=47&hl=en&start=1&um=1&tbnid =D_efMtUAkUTVgM:&tbnh=113&tbnw=120&prev=/images%3Fq%3Dgel%2Bcandle%26svnum%3D10%26um%3D1%26 hl%3Den%26sa%3DN
http://images.google.com/imgres?imgurl=http://thefavorbasket.com/images/orchidgelcandle-20046.jpg&imgrefurl=http://thefavorbasket.com/index.php%3Fmain_page%3Dindex%26language%3Den&h=48 0&w=600&sz=89&hl=en&start=3&um=1&tbnid=P8j4VCyUo2h JYM:&tbnh=108&tbnw=135&prev=/images%3Fq%3Dgel%2Bcandle%26svnum%3D10%26um%3D1%26 hl%3Den%26sa%3DN