Answer:
Black bodies are good absorber of light waves from the sun, while shining surfaces are good reflector of the light waves.
Step-by-step explanation:
Generally, a black surface or material tends to absorb light waves while under the sun, while a shiny surface is a good reflector of the waves. This is because the black material is a good absorber, and also a good emitter.
The shiny necklace can only absorb little light waves from the sun, thus it reflects most of the light waves. The reflection is the reason for the small circles of light seen around the yard.
However, when in a cool environment the black shirt would cools faster (good emitter) than the shiny necklace.