Use diamond for comment affordance to align with pull request file decorations.

src/vs/workbench/parts/comments/electron-browser/media/review.css

@@ -301,13 +301,20 @@
 
 .monaco-editor .comment-range-glyph.comment-thread:before {
 	position: absolute;
-	content: '·';
+	content: '◆';
+	font-size: 10px;
 	height: 100%;
+	line-height: 100%;
 	width: 9px;
 	left: -6px;
 	z-index: 20;
 	color: black;
 	text-align: center;
+	display:flex;
+	flex-direction:row;
+	align-items: center;
+	justify-content: center;
+
 }
 
 .monaco-editor.inline-comment .margin-view-overlays .folding {