What is the meaning of the phrase "set off to advantage?

Place something to look at its best.

She place the diamond on black velvet to set it off to advantage.

Her complexion was set off to advantage by the blue dress.

set off

1.

a. To give rise to; cause to occur: set off a chemical reaction.

b. To cause to explode: set off a bomb.

c. To make suddenly or demonstrably angry: The clerk's indifference finally set me off.

2. To indicate as being different; distinguish: features setting him off from the crowd.

3. To direct attention to by contrast; accentuate: set off a passage with italics.

4. To counterbalance, counteract, or compensate for: Our dismay at her leaving was set off by our knowing that she was happy.

5. To start on a journey: set off for Europe.

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