Dragons are notorious for hoarding treasure, and nothing will attract a Dragon more quickly to your altar than a gemstone bowl...
When working with Dragons its important to choose your stones wisely. The stones don't have to be polished, actually stones have a more natural energy when in their natural state. Each stone gives off individualized vibrations that you may or may not be able to feel. This is why you should handle several stones of the same variety before choosing one. Whether you pick up the stones in nature or you purchase them, make certain that the vibrations feel good to you. Stones attract & draw in the energy of the person or place they come into contact with. This is not always 'good' or 'positive' energy. If the stone attracts you, (If you like the look of it) but it feels wrong somehow, remember, a simple cleansing will remove the majority of negative energies from most stones, unless it's been used for a dark purpose, like a curse or hex.
Appropriate stones are set about on the altar to help attract and hold the attention of the Dragons upon which you call. Since circles of stones tend to concentrate and amplify energy raised within their boundaries, using stones set about a candle or even around the edges or at the four cardinal directions of a cast circle will intensify the magickal power the practitioner is creating for manifestation.
The Gem Bowl, which should be a regular part of your Sacred Tools when practicing Dragon magick, is an excellent place to keep your collection of stones. If your feelings tell you that a particular stone should be kept apart from the others, and this does happen on occasion, then you should keep these special stones in another bowl or separate container.
Another reason for separating a certain stone is if you are programming a crystal. Crystals can be programmed with specific vibrational energies, either deliberately or by being in contact with a person. A programmed crystal should be kept in a separate container, and label the container with the ritual purpose, if you fail to do this, you could use the crystal for a ritual that is not compatible or even in opposition to its programming.
Everyone will have their own preferences concerning the stones they choose, and I recommend following your intuition and the guidance of the dragon. The stones I used for dragon magick vary, but some that I use frequently are:
Septarian (dragon stone)
Dragon Blood agate
Crown of Silver
Golden Rutilated quartz
Brightest Dragon blessing,