The combinations are practically endless as are the purposes for which they are used. Having said that there are obviously some purposes which are more common than others. Healing is a very popular purpose, as is love. But all you need to do is be a little creative and you can come up with a grid for practically any purpose. Healing and love have already been mentioned but there are so many others. World peace, world ecology, psychic abilities, improvement in luck or finances, career and work purposes are all good ideas.
It is entirely a matter of personal choice as to what form the crystals and stones used take. Tumbled or natural it doesn't matter. There is also nothing wrong with mixing and matching types.
To make a crystal grid:
- Decide on your purpose.
- Decide on your master crystal.
- Decide which other stones you will use.
- Cleanse and charge all the appropriate stones.
- Write your intention in clearly understood language on a piece of paper.
- Decide where you are going to make your crystal grid - it should be somewhere it will not be disturbed.
- Cleanse the area you have decided upon by smudging (or similar).
- Decide which geometric shape you will use.
- Arrange the stones in the appropriate geometric pattern.
- Visualize filling the master crystal with your purpose.
- Visualize your purpose being achieved.
- Say a prayer of thanks.
It doesn't really matter what your purpose is provided that your intentions are good. The geometric shape used is also a matter of personal choice. It may be worth experimenting with different patterns as you may find that one works better than another for you.