Even if inclusions aren't visible to the naked eye, the vast, massive majority of natural sapphires have them. If you can't see any inclusions (using a magnifying loupe), it's probably a lab-grown sapphire. The fewer inclusions there are, the rarer the sapphire. As for grading, it goes Type 1, Type 2, and Type 3, with Type 1 having no visible flaws to the naked eye. Type 1 sapphires are the most valuable.
Rubies, like other gemstones, are also prone to inclusions and flaws. Rubies use a clarity grading system similar to diamonds, which is VVS, SI1, SI2, I1, I2, I3. VVS means very slightly included, and SI means somewhat included, and I being obviously and prominently
Inclusions are pretty common and should not be considered the most critical factor when determining the value of a ruby, especially for jewelry. The greatest thing you can do is to avoid apparent inclusions, such as chips, cavity flaws, feather anomalies, crystal inclusions, etc. So it's best to stay in the VVS to SI2 range.