If the necklace is silver it means it was made using Sterling silver.
The "S" on a 14k ring typically denotes the purity of the gold used, indicating that the ring is made of 14 karat gold. This means that the ring is 58.3% pure gold, with the remainder being other metals to strengthen the gold.
In the context of gold, "s14k" usually indicates that the item is made of 14 karat solid gold. This means that the gold piece is 58.3% pure gold, with the remaining percentage being other metals for strength and durability.