You can just see the hallmarks in the right hand image. It’s had a test drive and works well , though noticeably heavier than a normal crochet hook. This one is just about 4.5mm. I could make other sizes.
Unsolicited, the recipient of the gift emailed me to say
“I just wanted to let you know that I love it. It is heavier than a regular crochet hook but it’s a reassuring weight and has a lovely glide when you use it. “