How to tell a refill

[gaga4goonik]

okay, so this is probably a really stupid ? that proves what a novice i am. i bought a 20oz lava lamp off of ebay. description said blue with red lava. i got it today. the lava is completely opaque and no light shines through. it's a weird burnt orange/brown color (which makes me think it's just wax that's been tinted/played with) also, it's one of the 20oz with the silver cap and base. but the bottle cap is white instead of golden like my others. it has the label with a much longer number than the others too. i'm just lost:(