Are you sure it says 1dc3tog or is that what you remember? I can't always trust my memory, so I wonder if yours slipped a bit. 1dc3tog doesn't make sense to me either.

Is the pattern available on-line or in one of the popular books?

Hey Pauline,

This is the pattern (it's on this website): http://crochetme.com/patterns/turtle-shell-hat
It definitely says that, and I just can't figure out what exactly lozenge stitch is supposed to be.

http://www.articleclick.com/Article/How-to-Zigzag-Lozenge-Stitch-in-Craf...

Don't know if this link will help...

You could also try e-mailing the pattern creator through her blog or this site. Seems like she's willing to help.

I had a look at that site last night, it still doesn't make a whole lot of sense to me. I tried leaving a comment for the pattern creator, hopefully that'll help.
Thanks for your help though :)

I see you got an answer. Good. I guess it's a cluster stitch. The description sounds more like a half double crochet cluster than a double crochet cluster which would be a different height stitch.

Yeah, I think it is really supposed to be a cluster stitch, not dc3tog. You would use a stitch like dc2tog when you are reducing stitches in a pattern.

So I should be doing clusters of three half dc? Even after the pattern creator explained it, I still ended up with a wonky hat :-\ Maybe this is one I'm better off making a pattern for myself.

I don't know which it is. She called the stitches double crochet, but she described half double crochet. Make a small swatch of both to see which looks more like the photo. It's a cute hat, but, as she said, there may be errors in her pattern.