Hello community,

I need to create a diamond shape, but in the context of a sewing pattern, meaning my diamond shall look like this:

I created this shape myself and while it looks pretty well on the first look, the upper half is actually not a perfect mirror image of the lower half.

I tried a new construction by using the star/polygon tool with 3 corners, giving me a triangle. I duplicated the triangle and rotated it holding the Ctrl key. After some moving I ended up with this:

I have 2 problems here:
1) Even though I used Ctrl during rotation the triangles seem not to be 100% on a horizontal line.
(I used the Ctrl key during rotation of the initial triangle as well as for rotating the duplicated triangle)

2) Aligning the two triangles next to each other obviously gives me 2 lines next to each other, leading to a double line width.

How can I fix these problems? Is there maybe a better, different way to construct such a shape in a perfect way?
Thanks for any support on this

...another possibility would be to continue with your "imperfect" diamond.
If you use the node tool (F2) and mark one node you should see its x,y coordinates in the tools control bar. This way you can modify and precisely place every single node. This might be helpful e.g. if you need a very special polygon.
Of course, you can use @tylerdurden's diamond and simply resize it to the exact dimensions you need.

Sounds like the same rendering gap issue of anti aliasing, recently discussed in this topic.

I'd go by Tylerdurden's solution above.

Note: the mentioned issue is not an inkscape bug but a conceptual issue with vectorgraphics (being it 2D or 3D) present in most renderers.

Thank you all for your information on how this diamond can be drawn and what causes the display problems.
I ended up following tylerdurden's way, just great! Sometimes things can be quite easy once one knows how to do it

For the records, this is the "perfect" diamond (black) over my red, imperfect diamond: