I have used an ivory linen card with gold matting for this card to match the colour of the flat back pearls.
I drew a faint heart outline as a guide and stuck the pearls down with a pva glue which dries clear.  I left a small gap between the pearls for the line to show through.
If I make this card again, I would draw the heart with a beige/mushroom coloured  fine Marvy le Plume  pen and perhaps make the heart a tadge narrower.
 
