Each gem contains its' own energy source, and in some case, interactive effects.

Take a ruby. Prepare a stone in a specific manner, split it in half, and affix both halves to the top of two different pens. Move one pen, the other one shifts, drawing across the page. The result is the communication system we rely on, rather than this network of yours.

Or garnets. They may influence liquid- shape and cut a garnet appropriately, manufacture it according to various specifics, and give it to an archer to affix to their glove. The garnet will draw moisture from the air towards itself, and away from the bowstring, allowing your force to continue to shoot during the rains. Similarly, smokestone may be placed in a chimney, to ensure the clean drawing of smoke from a fire- if you can't afford a larger fabrial that would eliminate the need for a fire by simply producing heat.

[Even these designs are all simple ones, but it's a technology that's still being rediscovered.]