Gem Price Forecasts
This graph is the visual representation of my forecasts about the prices of the Gem Exchange.
We have the upper limit which is determined by Arenanet's Standard Buy Gems option and the lower limit depends on how cheap the gold is.
This means that the higher the Gold-Gems conversion rate is, the most likely the best option for buying gems will be to buy them directly from Arenanet and viceversa (kinda obvious).
However, it is useful to know which is the current trend (and you can see it on sites like gw2spidy) and have at least an approximate idea about what values it will make the market reach.
From my experience and calculations, this is the most likely scenarios: a conversion rate between 9 and 18 golds per 100 gems with mono-tones trends.