Here is an interesting technique I learned from someone painting ceramic bisque near me. He was painting a dragon and the dragon was on a rock that was on a bed of quartz-like gems. He was taking a long time on the gems and it made me ask him what he was doing. He explained as follows;
What he was doing was giving the gems a realistic look by giving it depth. Here is a step by step.
Step 1: Paint 2 coats of your base color.
To start, you must decide the base color of your gem or gems. I am going to chose purple for this technique. Some dark red and blue would be nice too. Go ahead and paint one coat of that color and wait for it to dry. After dry, paint another coat and wait for it to dry as well. For more vibrant colors like red, royal blue, and fuchsia, try adding 1 or 2 more layers since those colors can show brush strokes more easily, which leaves you with uneven tones.
Step 2: Dry brush layers on top of base color.
After you have applied the base color, use another color, one similar to the one you are using as the base color. Now you must use a technique called dry brushing which consists of dipping your brush into the paint and dabbing it on a piece of paper or napkin till the brush is almost entirely dry. This will allow you to add small amounts of the color you intend to use to give the gem depth. In this example, we are going to use a light purple and a red to add the layers on top of the base color purple. After your brush is dried, start passing the dry brush on the gem in order to add these layers. repeat this step with lots of colors. Try adding 5 different colors 5 times each. That is a total of 25 very thin layers that add depth.
Step 3: Add highlights.
After adding at least 25 layers of 5 different colors to the gem you can start highlighting the gem. Keep in mind where you want the light source to come from and make sure all of your gems shine according to the location of the light source (Also keep in mind that different facets of a gem shine in different directions, regardless of light source). To add highlights you simply use the same dry brushing technique you used to add layers, only this time you will focus on the extremities of the gems. Using white or a very light color related to your base color, dry-brush 1 or 2 layers on these extremities. This will give it the shine. Take your time and make sure your brush has very little dry paint. You might want to learn how to antique an item and antique the gems you just painted to give them overall depth but it isn't required
That pretty much is the technique used to make a gem look real. It comes out amazing! If anyone has a different technique please post it! Also, if you have painted something with this technique, posting it here would be awesome!
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