For wearing a gem, apart from the lordship one also needs to consider the placement of the planet. Mercury is also 6L and is placed in dire enemies Mars' house in rasi and navamsa. Also, Capricorn ascendants should only wear Mercury stone if their Mercury is well placed in 1, 2, 5, 9, and 10th house. Your's is inimically placed in 4th in rasi and 3rd in navamsa. So, sorry I would not advise you to wear Emerald.
Furthermore, Mercury is placed in nakshatra of Venus... so IMO, all you need is just the stone for Venus (diamond).
Regarding stone for Saturn (blue sapphire), again I am a bit skeptical in advising anyone to wear stones for natural malefics as you need to keep tracking the transits of these planets. Current transit of Saturn is over your natal Saturn, this transit is called as Saturn Return and is particularly associated with change in responsibilities, stress, mental distress and anxiety. Usually, blue sapphire is not advisable to wear during Saturn's malefic transits, return, and sade satti. Saturn will be in Venus' house Libra till 2014. Next transit of Saturn will be through his dire enemy, Mars' house. So, sorry I would not advise you to wear Blue Sapphire till the end of 2017. You may wear Rudraksha for Saturn or fast on Saturdays.
This is the third post, I am telling you all you need is Diamond and it will take care of Saturn and mercury effects.
- Saturn is placed in Venus' house in rasi
- Current transit of Saturn is in Venus' house (not considering its retrograde in Virgo)
- Saturn is placed in Rahu's NK, which is placed in Venus' house and Rahu is conjunct with its depositor, Venus.
- Mercury is placed in NK of Venus.
- Venus is in own house
- Venus is the most impt planet in 2012.
However, I strongly believe that your current problems are because of Ra MD. So you are advise to do the necessary remedies as suggested in my earlier post till the end of Ra MD.
But, if you feel I lack basics, than you should just use your free-will.