Quote: Dragonhaque

então só + uma duvida pra esclarecer de vez se eu tenho lagoa + gemstone mine, eu posso add qualquer cor na lagoa né? pq ele ñ tem efeito de substituição na gemstone mine, eu só retiro um marcador e add qualquer cor. então lagoa faria qualquer cor tb, correto?

Isso.

Por enquanto só quando a mudança de mana gerado estiver no mesmo custo pra gerar a mana que a lagoa leva em consideraçao.

Quote: Dragonhaque

eu tenho lagoa + gemstone mine, eu posso add qualquer cor na lagoa né?

Sim.

Quote: Planeswalker

Por enquanto só quando a mudança de mana gerado estiver no mesmo custo pra gerar a mana que a lagoa leva em consideraçao.

Reflecting Pool leva em consideração qualquer efeito de substituição que poderia atuar sobre a habilidade de mana, inclusive efeitos de substituição gerados por outras cartas, como Naked Singularity.
Em negrito, a parte que explica tudo isso.

Naked Singularity
5
Artifact
Cumulative upkeep 3 (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
If tapped for mana, Plains produce R, Islands produce G, Swamps produce W, Mountains produce U, and Forests produce B instead of any other type.

Mana
Mana is the resource used to play spells and is usually produced by lands. Mana is created by mana abilities (and sometimes by spells), and it can be used to pay costs immediately or can stay in the player's mana pool. See rule 406, "Mana Abilities."
The colors of mana are white, blue, black, red, and green. The types of mana are white, blue, black, red, green, and colorless.
Colored mana costs, represented by colored mana symbols, can be paid only with the appropriate color of mana. Generic mana costs can be paid with any color of, or with colorless, mana. See rule 104.3.
The spell or ability that adds mana to a mana pool may restrict how it can be used. An ability might produce mana that can be used only to play creature spells or only to pay activation costs.
The type of mana a permanent "could produce" at any time includes any type of mana that an ability of that permanent could generate if it were to resolve at that time, taking into account any applicable replacement effects in any possible order. Ignore whether any costs of the ability could be paid. If no type of mana can be defined this way, there's no type of mana that that permanent could produce.
To tap a permanent for mana is to play an activated ability of that permanent that includes the {T} symbol in its cost and produces mana as part of its effect.