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By on October 8, 2009, with 32 Comments

This is a diamond variation of the Craik O’Brien Cornsweet illusion. What you have to do, is to look at each row of diamonds below. Does each row appear darker than the row above it? It sure does to me. In reality, all of the diamond shapes present in this figure are in fact identical in luminance. The reason for this illusions, is that when combined in this pattern, the diamonds near the bottom are perceived darker than those near the top!

Blue Diamonds Optical Illusion

UPDATE: Check out the video below, recently uploaded on YouTube. This guy showed how this illusion works in real life:


32 Responses
  1. Care Bear says:

    Not really. The colors are graduated, that’s all. Nice to look at, though. I love blue.

  2. Jimmy says:

    1st comment!very nice illusion

  3. 1st (or second comment) but great illusion.is it real?its very hard to believe

  4. Ashley says:


  5. Manu says:

    And, if you stare at the center for 30 seconds or so, you will be able to see nothing but a blue square and no diamonds. Can anyone do it too? The diamonds disappear

  6. Luca says:

    They are not the same color. I was intrigued by this so i took the picture into photoshop, where i clicked the eyedropper around it in random places, and the shade of blue was changing.

  7. No one, says:

    huh…cool…who knew a simple shape could be so….like an illusion?

  8. Ms.Observant says:


  9. Dee says:

    Blue diamonds don’t appear to be all the same luminance. Paste the image into a picture editor then paste another copy right next to it. Flip the second copy 180 degrees and slide it over to match up the edges of the diamonds to make the pattern seamless. There’s a clear difference. Aside from that, if both rows of diamonds were the same, there would be no line demarking where they met and the whole center would be one color, not showing any diamonds at all.

  10. Michael says:

    I think everyone’s misunderstanding Vurdiak. All of the diamonds are identical, though each becomes gradually darker towards the bottom.

    Put in this pattern, it does appear that the bottom diamonds are, on the whole, darker than the ones on top. Rather than using Photoshop, just cover up everything around the bottom of two diamonds on different rows with your hands. Compare them, and they look identical, but when you remove your hands, they suddenly look different again.

    Cool illusion, Vurdiak, and congrats on your ever-improving English!

  11. Peet says:

    I wonder if the pattern had 4 full rows and two half rows of diamonds if the rows would appear to get darker as you moved lower, or if only thetop and bottom rows are affected (top appears lighter and bottom darker).

    I rather suspect this is due to the top and bottom rows being just half diamonds and it is their effect giving the illusion.

  12. Gordon says:

    Cool effect. It also produces an image similar to a stereograph, providing 3D depth.

  13. Jenni says:

    I agree with Michael – the colour is graduated, and the same for all the diamonds

  14. Rummy says:

    Michael seems to get it, I didn’t at first either and did a little thing with the image in paint. What Vurdlak means to say is that all the diamonds are identical, and thus collectively identical in luminesence. Each diamond IS graduated in colour, going from dark to light, but all the diamonds used at the exact same ones tessellated, a very intersting effect.

  15. Detective Kitty says:

    this is actually pretty brilliant…no need for explanation again…but this is pretty awesome….

  16. salad says:

    OH! I just got how it works. Duhhh. Wow, that’s insane! Cooooooool.

  17. jeanbrown says:

    Yes, Manu I see what you mean, cool!

  18. Raiker says:

    i can´t belive it good illusion

  19. T Rich says:

    I see how they’re all the same colour..

  20. Nigel Otto says:

    Kickass, I bet they are all the same color though

  21. Rino Rubino says:

    open the image with photoshop,make a selection with the polygonal lazo tool that surround one of the diamnds and then make ctrl-j to copy the selection in a new level,then with the move tool just move around the diamond,you’ll ssee that they have all the same luminance :D great one!!!

  22. rey says:

    No need for photoshop. simply grab the picture and flip it over the darker colors goes up!

  23. Emily says:

    It is simply because each shape has the same gradient. Top dark bottom lighter, Therefore the bottom row only shows the darkest half and the top only shows the lighter half…..When comparing ones in-between the bottom section is always going to appear next to the top and darker section below…its pretty easy to reason.

  24. vegas adam says:

    i love emily’s explanation but its still way cool like magic or slide of hand it makes you think youe seeing things when nothing has changed

  25. jennifer abigayle says:

    if you stare at it long enough all the different shades go away and it is just one blue picture!! soo cool!!!

  26. Kelly says:

    The diamonds are all the same, except they are graduated. This is why they appear to get darker. They are lighter towards the bottom.

  27. I just found your great site and scrolled through the first hundred or more illusions…

    Some months ago I had seen this video on YouTube, and I quickly rebuilt the diamond pattern in Photoshop. I printed it and gave it to one of my students (she’s 8 years old) who was completely amazed by this simple yet effective illusion. To her, it was “pure magic!” :)

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