How to change background color of ion-item inside ion-list onhold event in ionic2

suppose i have ion-list

    <span *ngFor="let user of users | async">
      <a ion-item (click)="openItem(user)" (onhold)="selectUser(user.$key)" *ngIf="user.$key !== uid" color= colorVar>
        <ion-avatar item-left>
          <img *ngIf="!user.picture" src="assets/img/profile.png">
          <img *ngIf="user.picture" src="{{user.image}}">

when i try to change color using the colorVar variable it changes the color of all items inside the list while i want to change color only that specific item.
Please help me out
My main objective to select ion-list item onhold gesturePreformatted text

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