I had two of the same size casserole dishes that got stuck together and would not budge. I tried everything: hot water on the outside, cold on the inside; freezer; only cold water; only hot water; cold water outside and warm water inside. I went back and forth for THREE years and each time I gave up and put it back in the cabinet. Then one day I finally gave up after, for the last time, trying all different combinations of trying to separate the two casserole dishes. So, I opened the trash bin and dropped them inside the trash.....GUESS WHAT? THEY SEPARATED!!! Really, having them drop into the trash caused them to separate! Now, that was one happy trash picking day!!
So, with my experience, I found that vibration works best. Put a folded towel on the countertop. Turn the candle holder over and tap it lightly in quick succession to cause a vibration where the object inside will loosen and fall out.