Two observations. 1: When photographing reflective surfaces (like a highly polished knife blade) be aware of what is being mirrored in the surface. You either want nothing to show, or you want what you specifically want to show. But never just random objects or light appearing.
2: Remember the rules of composition. The center of the field is boring. Try to locate objects in the primary points of interest. These are the four spots just in the from the corners in a rectangular field. Divide the field into three equal parts on the horizontal and the vertical. This means two lines going each way. Where the lines cross are the points of interest. This is where the eye is naturally drawn when looking at the image. Always try to have something interesting in at least three of those four spots.
Also, you want enough information in the composition to be interesting, but you don't want it too "busy." Don't overload the composition with objects.
Of the examples posted, I think the one with the knife and coins is best. The lighting and exposure on all of the images looks good. Very nice work. Try using a wide-open aperture setting. The larger the aperture the shorter the depth of field. It makes for some intriguing photos when the nearest object is in focus and the ones in the back are just a little fuzzy even though they are just a few inches away. It's a means of identifying the most important subject in the composition, too.
Oh, one more thing. Try to avoid crowding the edges of the field. When the subject is very close to the edge it creates a lot of tension. Now, if that what you want, then fine. But these images sort of strike me as relaxed and sophisticated. Either leave a nice cushion of space at the edge or go ahead and let the object escape the confines of the composition a little. It's routine to cut the very top of the model's head off in fashion photography.