The diagonal composition is good but I think the main problem is the lighting with half of the image in shadow. You needed to either have it all in shade or all in light for it to work better. The background adds some interesting color and textures.
Using a less distracting or plainer background would have distracted less from the subject. alternately, you could have placed the object higher up on the table, and blurred out the background with a low fstop...
Very cool! I love the colors of the flowers, and the rainbows projected onto the tabletop in their shadow. But a bit tighter crop might be better, and it kind of feels unbalanced with the light only illuminating one side. Also, the brightest spot in the image is at the center of the top edge, drawing the eye away from the main subject. But a beautiful shot nonetheless.