Currently I have a slow attack speed weapon for my Barb in D3. It has a socket. Should I add a Ruby or Emerald?

**Answer**

Time for a bit of math. Let’s define the following:

**RubyDamage**: The damage-per-attack added by imbuing a ruby**EmeraldCritDamage**: The percentage of damage-increase due to a critical hit added by imbuing an emerald**AttackSpeed**: Your attacks-per-second**WeaponDamage**: Your current damage-per-attack*(including bonuses, like from your primary stat)***CritChance**: Your current percentage (from 0 to 1) per hit of getting a critical-hit.**CritDamage**: Percentage of damage-increase due to a critical hit

Using a ruby will add

```
RubyDamage * AttackSpeed * (1 + CritChance*CritDamage)
```

to your total expected DPS, while using an emerald will add

```
WeaponDamage * AttackSpeed * (CritChance)(EmeraldCritDamage)
```

to it. You only want to use a Ruby if the first expression is larger than the second expression; that is,

(first expression) > (second expression) RubyDamage*AttackSpeed*(1 + CritChance*CritDamage) > WeaponDamage*AttackSpeed*(CritChance)(EmeraldCritDamage) RubyDamage*(1 + CritChance*CritDamage)/(CritChance*EmeraldCritDamage) > WeaponDamage

Thus you only want to imbue a ruby if the expression

```
RubyDamage*(1 + CritChance*CritDamage)/(CritChance*EmeraldCritDamage)
```

is greater than your weapon damage+bonuses. Note that this damage will increase as your primary stat goes up, so in general the emerald is the better choice for the long-run. **Notice also this equation does not depend on your attack speed at all**.

**[Edit]** To make this easier to make sense of, I’ve created a graph:

### How to read this graph:

First, find your critical-hit damage% and critical-hit chance% *(as shown on your detail tab in-game)*. Find that value on the above chart, and get its approximate value.

Next, take your `damage`

*(as shown on your character sheet)* and divide by your `attacks per second`

*(as shown in the “details” tab)*.

If your damage *(divided by attack rate)* is **larger** than the graph-number, use an Emerald. But if the damage is **smaller** than the graph-number, use a Ruby. If they are approximately the same, you could use either, but I would recommend an Emerald, since it will scale better as your damage goes up.

The above chart is for Flawless Square gems. The other gems are largely similar:

- Chipped
- Flawed
- Normal
- Flawless
- Perfect
- Radiant
- Square
- Flawless Square
- Perfect Square
- Radiant Square
- Star
- Flawless Star
- Perfect Star
- Radiant Star

So, in general, **if you have low damage and low crit-chance, use a ruby; if you have high damage or high crit-chance, use an emerald**

*(though if you have high crit-chance but low damage, you might want to double-check here)*.

**Attribution***Source : Link , Question Author : Confused , Answer Author : Community*