I'm making this logo for a website for practice (just new to all this by the way) and I'm struggling to make the circle/ring surrounding the coffee cup look sleek and 3D.
I feel like the outside of the ring is sleek but when it gets closer to the inside, there's something wrong, as if it's too sharp or maybe the gradient isn't right. I don't have a clear idea on how to make the entire thing look realistic/sleek 3D.
You could give the light some directionality so that the ring is highlighted on one side, and darker on the other, to give the illusion that it's a 3D object. Here's a simple way you could do it.
Create a large circle with a thick stroke, light brown, and convert stroke to path, draw a circle with a thinner darker stroke inside the ring
Move the darker circle off to one side
Blur the darker circle
Copy the lighter circle. Select all and group. Then paste in place, select all and do Object > Clip > Set clip
You could then take this a step further by adding stronger white highlights. I made the highlight using a white stroked arc of a circle, and added a Power Stroke effect to create the variable width.
For added silky smoothness, add a slight blur to the highlights
It's not realistic drawing. Geometry of the coffee cup and the saucer below the cup is totally distorted, but it's distorted in a playful way, so I cannot see a reason to fix. (see Note 1)
One possibility to connect your ring better to the rest of the image: Make the ring a part of a tray. (I inserted a filled circle).
Compensate the contrast loss of the texts! Make them darker. I tried to do it by increasing the contrast, but it affects the colors, too.
It's possible to draw the ring in Illustrator by 3D-revolving a small circle. Illustrator makes geometrically sound shading automatically. Directing the light downwards gives this ring with zero effort.
Inkscape does not have this 3D effect, so making the same shading in Inkscape needs some work You can layer 2 rings with opposite radial gradients to get this:
It needs 3 shapes. They are separated in the next image. The white to black linear gradient is the opacity mask for the "light to the outer edge" -ring:
The placements and the colors of the radial gradient stops are critical. These gradients needed only 2 stops. here's the "light on the outer edge" -ring. The brightest spot is slightly off from the edge.
Note 1
The opposite: Trying to build it of elementary 3D models makes it geometrically right, but removes the handcrafted appearance. It's too plastic to be a drawing. Without a pro quality 3D program (Maya, Blender etc...+ plausible materials and light environment) it's far too simple to be a realistically rendered 3D job. An example:
