Please note that I have included only gems in EC 1-2-3. There will be better alternatives as you move on.
In some places I have used 2 gems.
Note that though Rose Quartz is pink, it is widely used on the green Heart Chakra. This is due to its special qualities. You can change as per your likings once you know the attributes of gems to be used.
You can also place gems directly in Organs. Like you can place a Ruby in the Pancreas of a diabetic patient. Ruby contains Chromium which is good in reducing Diabetes.
Amber & Citrine in Stomach & Small Intestines to help in ulcer & colic conditions.
I hope this helps.
God Bless
