Create three vertical dots (ellipsis) inside a circle

Question

You could just use :after pseudo-element with content: '•••' and transform: rotate. Note that this is the bullet HTML special character •, or \u2022.

div {
  position: relative;
  background: #3F3C53;
  width: 50px;
  height: 50px;
  color: white;
  border-radius: 50%;
  box-shadow: 0px 0px 15px 1px #4185BC;
  margin: 50px;
}
div:after {
  content: '•••';
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%) rotate(90deg);
  font-size: 15px; 
  letter-spacing: 4px;
  margin-top: 2px;
}

<div></div>

Improving on Nenad Vracar's answer, here's one that doesn't use text (so it's font-independent) and everything is centered nicely:

div {
  position: relative;
  background: #3F3C53;
  width: 50px;
  height: 50px;
  border-radius: 50%;
  box-shadow: 0px 0px 15px 1px #4185BC;
  margin: 50px;
}
div:after {
  content: '';
  position: absolute;
  left: 50%;
  top: 50%;
  width: 2px;
  height: 2px;
  margin-left: -1px;
  margin-top: -1px;
  background-color: white;
  border-radius: 50%;
  box-shadow: 0 0 0 2px white, 0 11px 0 2px white, 0 -11px 0 2px white;
}

<div></div>

Yet another answer, same as others except:

• it uses the vertical ellipsis character (U+22EE)
• text-align and line-height to center the content
• does not use any pixel value

.discussion:after {
  content: "\22EE";
  /* box model */
  display: inline-block;
  width: 1em;
  height: 1em;
  /* decoration */
  color: #FFFFFF;
  background-color: #000000;
  border-radius: 50%;
  /* center align */
  line-height: 1;
  text-align: center;
}

<div class="discussion"></div>
<div class="discussion" style="font-size: 2em;"></div>
<div class="discussion" style="font-size: 3em;"></div>
<div class="discussion" style="font-size: 4em;"></div>

Note that U+2807 is actually a Braille pattern and the dots are not supposed to be centered.

Use this code.

.discussion {
  width: 20px;
  height: 20px;
  border-radius: 50%;
  position: relative;
  background: #2d3446;
}

.discussion:after {
  content: '\22EE';
  font-size: 1em;
  font-weight: 800;
  color: white;
  position: absolute;
  left: 7px;
  top: 1px;
}

<div class="discussion"></div>

Hope this helps!

I hope this is what you wanted! Otherwise feel free to ask.

.discussion{
  display: block;    /* needed to make width and height work */
  background: #2d3446;
  width: 25px;
  height: 25px;
  border-radius: 100px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.discussion:after {
  content: '\2807';
  font-size: 1em; 
  color: white;
  margin-left: 15%;
}

<div class="discussion"></div>

Using text dots

.discussion{
  width:50px;
  height:50px;
  text-align:center;
  background-color:black;
  border: 2px solid red;
  border-radius: 100%;
}
.discussion text{
  writing-mode: tb-rl;
  margin-top:0.4em;
  margin-left:0.45em;
  font-weight:bold;
  font-size:2em;
  color:white;
}

<div class="discussion"><text>...</text></div>