It most likely means the percentage of gold in the material.
The number "928" on your gold necklace is likely a marking to indicate the gold purity, which is usually measured in karats. In this case, "928" likely means that the necklace is 22 karat gold, indicating that it is made up of 91.6% pure gold.
928 refers to the purity of the metal used to make jewellery.
It means it is 14 k gold.
9999 gold necklace with a 9999 gold cross price tag
?
It could indicate KaraT Plated, meaning that the necklace is gold plated.
White gold
Is DM real gold
gold
What does 826 on a ring mean
Nope not at all