TOOLBOX: Diamond 1 Corner Rounder Review

Toolbox: Diamond 1 Corner Rounder #tool #review #paper
I’m pleased as punch (no pun intended) with the Diamond 1 Corner Rounder I recently bought. It comes with a 1/4″ corner rounding die, which is great, plus ordered a couple of other dies as well.

It will punch a whole stack of paper/cardstock/etc at a time, which is super handy for rounding the corners on pads or books. The extra scrap falls down a hole at the back, into a trash drawer. There is another drawer at the front for extra dies, and tools.

Toolbox: Diamond 1 Corner Rounder #tool #review #paper

The extra dies I ordered are namely a wider diameter rounder, and a 45 degree straight cut (possibly because I was watching BSG at the time.) In total I have 4 blades, from a very small professional curve to a nice big friendly one. The blade pieces are a bit oily- I would advise wiping them down with a paper towel before hooking them on. The oil has never been on the blade portion, so it doesn’t transfer to the paper.

They look like this…

Toolbox: Diamond 1 Corner Rounder #tool #review #paper

Here are the cutting results from each blade: M (45 degree die), S (1/8″ die), M (1/4″ die comes with the cutter) and L (3/8″ die).

Toolbox: Diamond 1 Corner Rounder #tool #review #paper

Each die bolts onto the cutter with an Ikea style hex key. It’s very important to re-adjust the blue guides after replacing the blade, and from time-to-time while you’re using it. (If the blade is too close to the paper, or if it is slightly turned you get a small notch in the side of the curve. Look at the “S” example in the sample picture above. The curve goes into the paper, instead of going straight into the straight side.)

Toolbox: Diamond 1 Corner Rounder #tool #review #paper

Once you have your die blade bolted into place, the blue guides are loosened and adjusted.

Toolbox: Diamond 1 Corner Rounder #tool #review #paper

I cut several scrap pieces of Crane Lettra. It does well, but with a large stack there is a little variation in the shape of the curve from top to bottom. A stack 1/4 inch or smaller works best. These sheets were cut as a stack…

Toolbox: Diamond 1 Corner Rounder #tool #review #paper
The cutter has a nifty hole and drawer for catching paper scraps (though they will still get EVERYWHERE). The front drawer holds some of the things you need; a couple of blades, the hex keys, etc.


All in all I’m happy- my biggest complaint is the constant adjusting of the blue guides. But it’s worth it to get rid of those sharp, pointy edges (and so much better than craft rounders.)

What I love about this tool

• It’s simple and easy to use.
• I’m able to change out the dies for different purposes.
• It cuts clean and fairly consistently on a variety of different papers and card stocks.
• Good quality and value

A couple of drawbacks I’ve found

• The blade really cuts into the blue plastic underneath. The set comes with a few replacements, and I can see I’ll need to replace the original pad more quickly than I’d hoped.
• It’s really important to get the paper lined up in the corner just right, so you have to really keep your eye on how you are putting the paper under the blade. There are guides, but for some reason it’s easy to slant the paper one way or another.
• I want to round everything. In fact, I just might.

I bought this guy from Binding101 because they were the cheapest. It’s also available from an Amazon dealer. It took about 5 business days to get to me, which was great.

Note: I did not receive any kind of compensation for this product review. At Adventures in Making we love sharing information about our favorite tools and resources because we believe knowledge should be shared and that we can all learn from each other’s experiences.


  1. Kellie A says

    I am interested in purchasing one of these to make rounded corners on wallet-sized photos. It seems like it would work well for that but I’d love confirmation! Thank you!