Emerald Exchange

The Emerald Exchange lets you gamble Emeralds for Gold. It pretends to be a wheel but the real win chances aren't visually represented.

Spinning the wheel grants the Gold value, the value displayed before pressing the roll button, multiplied by the Multiplier it lands on.

The Emerald Exchange can only be used a limited number of times per day, determined by the VIP Level.

Win chance
Win chance according to the Official Hero Wars Mobile Drop Rates (probably similar in Web/Social):

But there is no information on how these numbers are used, in worst case resulting in even worse chances.

Emeralds Cost
The cost per spin is determined by the number of spins that you have done on that day. Starting at 20 Emeralds increasing by 5 each 5th spin, up to 95 Emeralds at the 76th spin onwards.

Gold value
The Gold value depends on the Team Level. The displayed value changes if the roll button is pressed!, therefore it always shows the Gold value of the next spin.

First Spin
The Gold for the first spin is calculated by:

$$\text{First spin} = 24000 + (\text{Team Level} * 150)$$

Subsequent Spins
For each spin a fixed amount of Gold is added (Multiplier = 1):

$$\text{Gold increase} = (80 + (\text{Team Level} / 2)) * Multiplier$$

Except at the time the Emeralds cost increases (each 5th spin up to the 76th spin), it uses a higher Multiplier.

Team Level 130 Table
Number of Spin, Gold and Gold per Emerald ratio for Team Level 130. Although there are jumps in the Gold and Emeralds value the ratio increases consistently.