What do you crochet with?
Neckstrings are not delicate, and the only time I have ever had one break is when one of the tips got stuck in something--like bending over a wrought iron table or something.  I mostly use tuff-cord because it is more durable to wear and tear than silk. I often crochet chain in with thread which  increases the strength and is great for heavier or more rough cut, heavy stones. 
What is Gold Fill & Gold Vermeil versus Gold Plate?
Gold Fill and vermeil are wonderful  affordable alternatives to 14k gold
Gold-filled jewelry has 100x more gold alloy than gold plated and because that layer is so much thicker, it means gold-filled jewelry lasts and stands up to wear and tear better than gold plated. 
Gold Vermeil is a common type of gold plating, which uses sterling silver as the base metal. Vermeil is more hypoallergenic and has a thicker layer of gold than normal gold plating, which is why you'll see it in stores selling fine jewelry. 
Neckstrings Jewelry works with gold fill and gold vermeil