A piece of jade will not change color under normal circumstances. You can scrape it with your fingernails and feel it. If it's not so smooth, it feels like rustling. I suggest you go to the local authoritative testing institution for testing. If it is not A, bring the shopping voucher to the local consumer association to complain and claim compensation from the merchant twice.

Here are some addresses for your reference:

Shijiazhuang jewelry and jade products quality inspection station 0500310311-5057711.

Tangshan Gold Gemstone Quality Inspection Station, No.23, Beixinche Road, Tangshan City, Hebei Province 063000 03 15-2825080

Hebei Jinyin Baoyu Ornaments Supervision and Testing Center No.318 Baoding Baihua Road 071051312-3026931