Alternative view of adapting AD&D gemstone dragons to Mystara
by Andrew TheisenInteresting. I haven't ever really looked much at the AD&D gemstone dragons as inspiration for Mystara because, as you note, they have always been a different sort of creature (both in terms of abilities- notably the psionics- as well as color/type).
If I were to use this information, I'd suggest that Saridor would more likely be an agent of Diamond, as Ruby dragons are Lawful in BECMI rather than Neutral, although that really depends on how strictly you want to interpret the alignment system vis a vis dragons in Mystara. If you'd rather adhere closer to the article, then Opal would work.
Otherwise, my suggestions would be:
Hrodel - Crystal Dragon
Tithonnas - Amber dragon
Smargad - Jade dragon
Charsima - Sapphire dragon
Aleithilithos - Onyx dragon
Two of those are straightforward and correspond to existing Mystaran gemstone dragon types (crystal, sapphire). The others I am just going strictly by "color":
a) Emerald and jade being "green" (and, to be fair, emerald is probably a better term for a gemstone dragon than jade, as jade isn't strictly speaking a gemstone [nor is crystal, for that matter])
b) Topaz and amber as "yellow/gold"; while topaz comes in a variety of colors (as do many of the other gemstones, frankly), I believe that amber is the most commonly found one
c) Onyx and amethyst are the outliers. Amethyst is more purple, for which there isn't a corresponding gemstone dragon, while onyx is typically black. Google tells me that there are purple onyx stones, though I suspect those are not natural, untreated onyx (I would have to do more research to confirm, though).
Obsidian dragons sound very similar to Onyx dragons. I haven't looked at that article you linked yet, so don't have any other immediate thoughts on this.
Blithenpaxantadravos sounds interesting, particularly in light of the other three-headed immortal dragon we know of, the Great One. Could Blithenpaxantradravos be his immortal (gemstone) dragon ruler counterpart? Maybe he secretly ascended to immortality a long time ago and has only emerged now to challenge the Great One in the draconic hierarchy by sponsoring the ascension of his own draconic immortal underlings (Sardior and two others representing the other two alignments). Maybe Blithenpaxantadravos is one of the "original" gemstone dragons from the other planar world of the Overlord, now trying to make inroads into Mystara and expand his power and influence among mortal dragons?