You will need to duplicate your diamond shape group
The reason for that is that the pattern of your texture doesn't really match the pattern of the reference. Here is why :
This is how your texture looks now (our diamonds have a lightly different shape due to the Vector curves node that I couldn't reproduce exactly) :
If you rotate each other diamond like you said, you will get either of those two here :
And none of those really look like the reference. The reason is that you actually managed to reproduce "half" of the reference, see :
The other half is just like the first half but rotated and with a bit of offset.
This is how I would do it :
First, I modified a bit your diamond shape group so that we can rotate the diamonds. I did that by adding a Vector Rotate node before the Vector Curves :
I added the angle of the rotation and your Normalize node as an input of the group for convenience. The normalize node actually controls the size of the diamonds so I named the input "diamondSize".
Using this node group with an input angle of 90°, I got the rotated version of the diamonds :
I can then mix them with an Add Node :
They are overlapping because I haven't offset the second one yet. They need to be offset about half of your tiling size on X and Y, which can be done by just adding a Vector Math Add after the Scale Node at the beginning :
giving this :
But the diamonds are too big, but since I exposed the diamondSize, I can change it by setting it to .15
instead of .3
:
I can feed that to the bump node to have the result :
Now all that is left to do is tweak the Vector Curves to shape the diamonds to your liking :
EDIT
I'll also suggest you to invert the output of the group node before plugging it to the bump node because, right now (if I copied your node setup accurately), your diamonds are going downwards instead of going upwards (White is up and black is down).