Is 0.47 carat enough to look sparkly?

Spread across a heart face as many small stones, yes. It reads bright at normal viewing distance, but each stone is small, so it will not have the depth of a single half-carat diamond.

How does 9K white gold compare with 14K or 18K?

9K is 37.5% gold, so it is harder-wearing in some ways but less tarnish-resistant and paler than 14K or 18K. White gold also needs rhodium plating to stay bright over time.

Is this suitable for everyday wear?

It can be, but pavé-set small diamonds are the fragile part. Avoid knocks and harsh chemicals, and have the settings checked periodically.

What chain does it come on?

The pendant is the described item; check the chain length and type on the listing before buying, since a heart pendant this size usually suits a fine 16 to 18 inch chain.

Is it a good gift for a partner?

The heart motif and white gold make it a natural romantic gift. It suits someone who likes delicate, classic jewelry rather than bold statement pieces.