How do i paint Dark liquid in a colored bottle?

[Erikjust]

I am currently in the midst of painting goblins and one of the miniatures has two bottle.
The gremlin smoking a cigar in the picture
http://cdn6.bigcommerce.com/s-ua4dd...e3be127_b__68809.1469815217.1280.1280.jpg?c=2

My question is if i want the bottle to be red like it is in the picture and at the same time give the illusion of a dark liquid inside it.
How do i paint it to look realistic?

 

[lesBarniques]

My best bet would be:

- choose the best angle you want to give that bottle illusion.
- paint the bottle dark like the outer rim of the bottle.
- gradually layer, wet blend in the red and then tone it lighter and lighter towards the middle matching the color scheme on the box,
- then paint on the specular light reflection to give that glass look