A thing to remember here is that these posts are strictly meant for the particular planet position. Like, today we are looking at Saturn in Gemini, so the description given here may change for you if your Saturn is although in the sign of Gemini but in conjunction with or aspected by other planets. --

Saturn is all that which we don't like in our life. Saturn is delay, frustration, restriction, limitation and anxiety. It is hard-work and labor. It is people of authority, like boss at your work place or father-figure at home. Saturn is Master and Servant both (depends on who uses Saturn in what way). Saturn is our Karmic debt from life. Saturn is the things we didn't treat too well in our past life. Saturn is our challenges and lessons of life. Saturn is old-age, teeth in human body, diseases, transformation etc. Saturn is discipline, organisation, structure, government, law & order etc.

Gemini is the 3rd sign of zodiac belt, so it represents many things related with 3rd house of horoscope like, Communication Skills (either written, oral or even by sign language), Marketing, Business etc. It is a sign basically related with communications and business ideas. Gemini is divided into 2 and half nakshatra of Mrigashira, Ardra and Punarvasu. Gemini's lord is Mercury, which is significator of Communications.

So now although Saturn is in a friendly sign of his natural friend Mercury, but this is the thing with Saturn that it does its job of delaying things in any house/sign no matter it is friendly/enemy/exalted/debilitated. So, here in the sign of communication, 1st of all if Mercury (lord of Gemini and Karaka of Speech) is not well placed, then these people may have speech disabilities as a kid. Sometimes it gives stammering impact on their speech. As a kid or growing up person, they can be absolute silent. Or they always feel that they wanted to say something and it turned out to be completely opposite and people misunderstood them. This is where Saturn impacts on their communication. This is where they start working on their communication, they start realizing their mistakes, they slowly improve their communications. And after few years of hard-work, they become good communicators.  As Gemini is also about written communication, they need to work hard in their written communications too. As Saturn is about long duration, this hard work needs perseverance. They can do excellent in marketing, technical fields and business but even there they need to improve with time and age. Hard-work is required with Saturn in any case.

Now, where does these things differ for different people born with Saturn in Gemini. It depends on the Nakshtra Saturn is placed in. So, if Saturn is in Mrigshira Nakshatra, then it will be impacted by Mars as Mars is its lord. If Saturn is in Ardra Nakshatra, then we need to assess Saturn's result through Rahu's position as Ardra is ruled by Rahu. If Saturn is in Punarvasu Nakshatra, then we need to check Jupiter's position.

Sign lord wise, Mercury is lord of Gemini. So, to really assess results of Saturn in Gemini, we need to see how Mercury is placed.