In this tutorial we will create a jewel in Blender. It is fairly simple. I recommend you do this tutorial if you are a noob, because it explains some basic features, but I suggest you read the tutorial syntax and the pages at the very beginning of this Wikibook first.
Modeling the jewelEdit
Start up Blender if you haven't already. There is a cube in top view (it looks like a square because it is in top view.) Delete it by pressing the X key. Then, to begin modeling, add a circle by pressing SPACE→Add→Mesh→Circle. Set the vertices to 10 and make sure it is not filled in. Then press OK.
Next, we will extrude the vertices down. First enter side view by pressing Numpad 3 on your keyboard. As you can see, the circle is flat and not filled in. We will give it some depth. Switch to Edit Mode (TAB) and extrude the circle by pressing the E key and selecting "Only Edges". Move the mouse down and click to confirm the position (you may want to limit to Z axis by pressing the Z key).
OK, what we just did is turn the circle into a hollow cylinder by extruding. But we don't want a cylinder. We want the bottom to be a nice tip. To do this, press Alt-M. This creates a Merging menu. Select "At Center". Now the bottom is a nice tip, like we want it!
Now we will edit the top of the jewel. Press A to deselect everything and press the B key. This enters Box-Select Mode. Drag a box over the top vertices to select them.
Now extrude the vertices upwards a bit (again: E key and "Only Edges"). Next, we will scale down these vertices to look a bit more like a jewel. Make sure the ring of vertices are selected and press the S key. This enters Scale Mode. Scale down the top vertices a bit and click to confirm.
To look around your jewel model use the Middle Mouse Button or Alt-Left Click. Your jewel is looking fantastic! But there's a big gaping hole at the top. We'll fix that. First, enter side view (Numpad 3). Now extrude the topmost ring of vertices but don't move them anywhere with the mouse. If you are feeling doubtful, just press 0 and then Enter (or just click right mouse button). This makes a duplicate of rings placed over the original. Next merge this new ring with Alt-M -> At Center. This merges the duplicate ring, thus filling up your hole.
At last! Your jewel is finished! Feel free to rotate around it and make further adjustments if you are more advanced with using Blender.
Switch back to Object Mode (TAB) and show the Shading Panel (F5). Enable the Material Buttons (click on the button with a red ball). Add new material by clicking on "Add New" button in the "Links and Pipeline" tab. Copy the settings in the screenshot below. If you are having trouble setting the precise value to a slider, just click on the number. This allows a manual type-in. First, make it green by setting R to 0, G to 1, and B to 0. Next set the alpha slider to 0.458 (it looks like an A). Now press "Ray Mirror" (raytracing reflection) to turn it on and set it to 0.13. Now press "Ray Transparency" and set the IOR value to set 1.44. When you're done it should look like this:
The finishing touchEdit
To improve the effect, add a plane underneath the jewel. In the Object Mode (TAB) press SPACE>>ADD>>MESH>>PLANE. Scale it 5 times using the S key. Then move it down a bit using the G key (press the Z key to restrict movement to the Z axis).
You may try to render your jewel now. Press the F12 key. You may find that camera doesn't see whole jewel. Move and rotate the camera (using the G and R keys) to set it in the right position. You may want to switch to "Camera View" (Numpad 0) and try out "Camera Fly Mode" (SHIFT F). Try also moving the lamp and see what happens.
I've found that the jewel looks best with Ambient Occlusion on. So go to the Shading window, then the World buttons, click the Amb Occ tab and click the Ambient Occlusion button.