Agree Charr, with your conceptualization In Vedic astrology, a given planet is described as having two kinds of attributes. It is either strong/weak (a quantitative attribute) or benefic/malefic (a qualitative attribute). One need not block ones mind by getting hung up on the terms. Many astrologers refer to these two attributes interchangeably, sometimes out of carelessness. On the other hand there also exist in traditional texts references to planets which are cruel, kruras -- the sun for instance -- but which are not necessarily malefic; somewhat akin to having a strict father or teacher! It is important to understand that gemstones are only capable of strengthening weak planets. They must not be used when the planet is a malefic. As a ready-reckoner, when a planet is in exaltation, in its own sign, in its special sign (moolatrikona), in the sign of a friend, in an angle or trine or in its angle or kendra of power (e.g., Jupiter, mercury in 1st, Venus, moon in 4th, Saturn in 7th and mars, sun in 10th), then it is strong. A similar brief consideration for determining a malefic planet would be: if it rules the 6th, 8th or 12th houses or if it rules the obstructive or badhaka house (11th, 7th or 9th signs from the ascendant if the latter is in a cardinal, mutable or fixed sign, respectively), etc. Evidently there is more to these attribute determinations than this. This has practical implications. For example, if the lord of the 6th house is weak (moon for an Aquarius horoscope), we must not recommend that the person wear pearls! On the other hand, if the sun is in Libra in the same horoscope, wearing a ruby (sun's gemstone) would improve matters pertaining to the 7th house!