Was reading a thread about colouring your bottle tops, nice thread but don't think i could go through painstaking OCD for that. Kudos for doing it, but still bit too much. Well trying this method and seems to be ok.
Drop of paint in the inner ring when using that colour, then a drop of PVA glue over it. The paint then rises to the top and the glue sinks and you have a gem like top. ( oh and drop of PVA before if its metallic paint, for it wont rise ) Dunno if it been mentioned before. Delete if it has.( and couldnt find the colour bottle top thread either )
Simple and quick.
happy painting